It seems to me that when it comes to ordaining female rabbis there are three main defensible views:

Why or Why not?

Judaism is a religion/people that is based on 3500 years of experience, tradition, and history. As such we have a LOT to honor and protect. Change comes very gradually to such an ancient system. This is a great protection as it assures that fads and assimilation do not abruptly alter the strengths that have enabled us to survive the worse persecutions ever experienced by any other group in history.
Also, because our beliefs are firmly rooted in Torah as preserved and interpreted through ongoing Rabbinic Tradition, we have a further built-in safeguard against assimilated beliefs and practices. This is where the demand for female ordination is just beginning to be seen. There are plenty of highly trained male rabbis to meet the needs of the Jewish community, more than enough. Yet SOME Jewish women (and some men) are now demanding to be like the other nations and have female clergy (consider I Samuel 8:5 in this regard). Whether this is a positive change depends on who one asks. The world we live grants full equality to women in every other area. Which brings us to position two.

Birth Pangs:

The ordination of female Orthodox rabbis appear to be inevitable. Its just a matter of time. The world and our people are very different than we were even 50 years ago. Gender "equality" is not a passing fad. Whether anyone approves or not, women are now completely integrated into all aspects of public and private life throughout the civilized world. Orthodox religious leadership is one of the very few hold outs. Female clergy persons are becoming ever more common among all of the non-Orthodox Jewish movements, indeed they seem to be on the verge of dominating it (which is leading some Conservative Jews to a return to Orthodoxy). Women are going to be Orthodox Rabbis one way or another, eventually. Either local congregations or overseeing organizations like the RCA will eventually accept them, or new congregations and overseeing bodies will be created, as is happening. It can be argued that the "Old Guard" Orthodoxy is adding to the already cancerous divisions among our people by holding fast to the line (which is not to say they wrong for doing so!). Orthodox Halacha is made by what the Jews do, not only by what the rabbis decree and more and more Jews are accepting this change for better or worse.

The Non-Orthodox began ordaining women many years ago. The Orthodox will as well, one way or the other. The current debates are but the birth pangs of this inevitable policy shift.

Not Now. Not Ever!:

Judaism has never been a static religion. It is always changing and developing as exampled by Rabbi Hillel changing the calendar and by modern rabbis ruling that local Orthodox rabbis no longer have the authority to make converts without the approval of power structures like the RCA ("Rabbinic Counsel of America"). Sometimes change is for the good, sometimes it is not. Some Jews and congregations will doubtless resist this change no matter what even after the policy is formally changed, but it will happen. Some women are already serving as defacto Orthodox rabbis.
In my male opinion, what the female rabbinate needs to do if they wish to be more speedily accepted as rabbis -- which the vast majority of non-Orthodox female rabbis have completely fail to do -- is resist the urge to make their gender a cause cé·lè·bre. In other words, they should NOT be "FEMALE rabbis" as most today are. They should be rabbis. My limited experience with female rabbis is that they tend to be FEMALE rabbis first. They talk about their gender and gender issues way too much. They are often preferential to other females. They too often focus on supporting POLITICAL groups like Women of the Wall that blaspheme the sacredness of the Holy Kotel for political purposes and not enough on strengthening the Jewish family unit. They too often fail to assist male congregants the same way they assist female members. They often ostracize males who hold to more traditional values and practices and they inevitably lead their congregations to the Left politically and religiously. Many male and female Jews just want a rabbi, not an activist in gender politics. Of course there are always exceptions and some female rabbis stick to just being rabbis. This is partially why so many Orthodox Jews say "Not now, not ever!" Female Orthodox even moreso than males in many cases. BUT in any case, it is inevitable. The only question is how Judaism will fare. Today female led congregation often close sooner rather than later unless they in an activist community where the rabbi's gender is a political statement. More and more Jews today are either becoming baal teshuvah (returning to orthodox observance) or they are abandoning our people.

My Point:

If prospective female Orthodox rabbis do as their non-Orthodox counterparts, Orthodox Jews are going to resist, pushing their inevitable inclusion farther into future and leaving more damaged souls on both side of the issue in their wake. Personally, I don't really care about the gender of my rabbi. What I care about is the Jewishness, the Torah observance, the wisdom, the compassion, the teachings, the cousel, the inclusion of both genders, the example set forth by the rabbi.and so on. This poses another serious problem because Jewish men are forbidden by halacha to be alone with a woman not their wife, dsaughter, etc. How can an observant male have a private conversation with a female rabbi? This will have to be addressed before Orthodox inclusion is possible.

Is the rabbi a good example and resource to ALL members of the congregation of traditional Judaism and its practice? Does the rabbi encourage the Jewish community to become ever more observant and zealous of Torah/Talmud study, of hitbodedut, of tikun olam? Does the rabbi lead the congregation and greater community in standing up for Israel? Is the rabbi a committed Zionist? That's what I want to see in a congregational rabbi. Considering that it is becoming ever more difficult to find these traits in any rabbis, male or female, Orthodox or non-Orthodox, gender needs to take a back seat now in my opinion.

What About the Mechitza?

The rationale for a mechitza, the partition dividing men and women in Orthodox shuls, is given in the Babylonian Talmud (Sukkah 51b, 52a). In Pirkei Avot 1:5, Yosi ben Yochanan says that a man who spends too much time talking to women, even his wife, neglects his study of Torah and will inherit gehinnom. During times of worship our attention should be on HaShem alone. This was the original purpose.
While times have changed and many may not understand its purpose, the original intention of the mechitza, in the form of a balcony, was established in the Temple in Jerusalem for the occasion of the Simchat Beit Hasho'evah (Water Drawing Ceremony) on Sukkot, a time of great celebration and festivity. Its use then dates back nearly to the dawn of our holy religion. Dividers were first established to preserve the modesty and attention of the worshipers not to penalize women etc.

Men are Morally Weaker Than Women:

Another consideration with both the mechitza and the ordination of female rabbis among traditional Jews is the long standing belief that men are more "fallen" by nature than women. The mechitza is seen as a protection of men to help them control their wondering lustful thoughts. Likewise with the rabbis, since men are believed to be less righteous by nature than women, having a male rabbi avoids needless potential temptations (there are some very attractive non-Orthiodox female rabbis!). If this view is "sexist," it is so against men, not women. At least, from the traditional perspective. This tradition judges that men are more prone to fall victim to lustful thoughts than women and that they need to be protected. Considering gender roles prior to 20th century this argument makes complete sense. Today most women have to work outside the home. The world has moved on. Many long standing gender assumptions are being reevaluated today.

Onward Through the Fog

The American cultural revolution of the 1960's and 70's challenged everything and some Orthodox shuls gradually began removing the mechitza. The Orthodox Union responded by adopting a policy of not accepting synagogues as new members if they did not have mechitzot. Existing member congregations were pressured to conform to this ruling.

As I said above, in my opinion, its a question of when all remaining gender barriers will fall, not if. But are we becoming more civilized by destroying the traditional gender roles, or is this a sign of our creeping decline?

Just my two cents worth.

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