I just had a friend that had this done to their cat, Pumpkin. Apparently this is fairly common and with very good results.

Pumpkin lives outside of Los Angeles (land of the fruits & nuts) and Doug was proud to say that he had the first cat on his block with a sex-change opperation! (sick, I know but that's my friend ) When Pumpkin was healed, Doug showed him off to all the "jealous" Toms in the neighborhood...

Keep us updated on Oscar.