Rowan Williams does not seem to have actually commented on the issue of ordination of women much except to say he does not have much of a comment - which is strange, actually, given his position. This is of course enough to rile people up who may hope that he would put an end to some of these things.
There are several main points that I have heard made about the ordination of women. They primarily involve the belief that the church position opposing ordination of women is wrong because:
1 - Ancients believed that women were not as morally strong or important as men. This is imbedded in language like "virtue" which literally means "manliness". Since this general philosophical opinion is now considered to be incorrect, all judgments of the early church and interpretations of scripture about women made by early theologians are under review. For example, in ancient times Paul saying in I Cor 14:34 "Let the women keep silence in the churches" etc. would be interpreted as a reflection of the general inferiority of women in spiritual affairs. Now many justice-seeking Christians assume it cannot be that and look for a local interpretation (e.g. some fear in the Corinthian congregations, or a desire not to challenge some existing authority, etc.) There are many scripture passages like this that make sense in a different way once the assumption of inequality has been removed.
2 - The first people given the commission to preach the gospel of the Resurrection were women (Matt 28:5-10 and synoptic). If they were considered suitable then, they should be now.
3 - Paul appointed female deacons (Rom 1:16. "servant" is the word "deacon" in Greek). At some point, this kind of service was made into an official church position that excluded women, though at this point they can no longer use scriptural backing of verses containing this word to explain or defend the diaconate because the category of deacon no longer contains the same items that it did at the time of Christ and Paul.
4 - The early church continued to ordain some women, even for categories of priesthood Paul thought should be excluded from them, (though the RCC challenges that all of these ordinations were by heterodox sects.)
Within some Protestant denominations, a priest is not considered to be conferred a special power or office by an officer of the church (another priest, bishop, etc.) All people are considered part of a priesthood. Therefore it follows rather automatically that if a congregation believes women are full members of their church, then they are equally eligible to be made a pastor (
pastrix). This is all rather simplified of course, but it does explain why these churches are more likely to "ordinate" women.
Position changes on homosexuality are driven by a belief that sexual attraction to the same sex as oneself, when it occurs, is usually due to an immutable genetic or congenital condition, or another condition which is not the fault of the person with the condition, and also that the same-sex acts do not themselves do harm (like drunkenness does, which is often a result of deep-seated conditions called "alcoholism.") These two together convince some theologians that scriptural passages appearing to condemn homosexuality actually condemn something else (e.g. male prostitution). This kind of reasoning is based on a strong hypothesis that definitions of sin in scripture all derive rationally from commandments to love God and to protect oneself and other human beings (e.g. Mark 12:30) and not some kind of inexplicable purely "spiritual" goal.
My version of arguments presented by Rev. Daniel Helminiak and others concerning specific passages in Scripture is in this thread at the wardrobe:
http://cslewis.drzeus.net/forums/viewto ... sc&start=0
I focused a lot more on language than other discussions that I have read on the subject, and I do a section on Matt 19:3-12 that I created in response to questions but that I have not seen in other literature on the subject (though I imagine it is there.) The treatments of various passages are distributed through the first three or so pages of the thread, because they are interspersed with responses and Q&A.
Responses to homosexuality issues should go on that thread, to avoid multiplication of homosexuality threads.
Sentio ergo est.