This issue came up a few weeks back on a British lesbian message board I frequent. One of the posters was a transvestite, and some people were uncomfortable with him posting there. There were a couple of other problems with this person too, so the decision was made to ask him to leave. However, one of the other members is a post-op transexual, and nobody objected to her prescence. Also, at one of the bars we go to (one of the best known lesbian bars in London) a regular is a transexual who’s only just started therapy and looks quite manly.
I do know, however, that a few women there were against post-op transexuals being considered real women. I started a thread on this subject several months ago. The argument one woman made was that they had lived as men for many years, and enjoyed the advantages of being male. Personally I think that the disadvantage of being ‘in the wrong body’ would far outweigh any advantages you get from the erroneous gender.
Some lesbians seem to be uncomfortable with the idea of transexuals, even to the extent of preferring not to date them. I think this is unfair but stems mainly from ignorance of what causes transexualism, and can be remedied with education and better acquaintance with transexuals. It’s certainly hot hardened intolerance.
As I said this is a British board, and of the three people who said they didn’t think post-op TS women really counted as women, two were American. It seems to be more of a problem in the US than here. I know that the big women’s fair in Minnesota (?) once actually did gender test on the door, and I could never imagine that happening here.
Nah, just because you’re gay doesn’t mean you’re not human. We grew up in the same society as everyone else and learnt the same prejudices. Most homosexuals even have to contend with internalised homophobia. In some ways the discriminated-against minorites can become over-protective of their position, and resent anyone who blurs the boundaries.
However, I would not say that most gay women don’t accept transexuals. It is more that the majority of gay women don’t feel vested enough in the subject to argue against those few women who are intolerant of transexuals.
A post-op transexual woman would certainly be accepted by me and my group of lesbian friends though, so if anyone reading this fits that description and is in London, let me know. 
(I can’t link to the aformentioned discussions, as the server on which they were hosted died and the threads are no more).