Though I'm female irl and play female characters, I agree that it's good fun to play other genders, and good for the game too...
though to be honest, there's no reason why anyone need know a player's "real" gender unless they're interested in looking for a RL relationship.
In the RP world, we pretend to be plenty of things that we would never dream of doing irl (like killing people ;P - at least I hope most don't dream of doing this irl... heh), so even if you're not comfortable irl with being with someone who is of the same gender as you, it doesn't really matter IC or in RP... That's the joy of Role Play... that you can take on another identity that is not real.
Having said that.. I happen to be a sucker for trying to get to know people OOC too ;P So I don't blame those who (like me), try to get to know players irl as well as ic...
What I do find incredibly annoying though, are players who are simply looking for "mates", or female players to be their girlfriend or wife, with little focus on the RP or character's personalities, etc...
It's boring to think that irl you would date someone, or marry someone, just because they were a woman or a man... The same goes for in game... It is much more interesting for a relationship, romance, or flirtation to occur because of the characters' personalities and the context of interaction. The ones that develop through RPing are always more exciting than ones that are decided upon in an instant upon first meeting someone.
Now, if you want to know what I really think... the real shortage in PS are female chars who are intersted in being with other female chars, and who aren't already attached to jealous male chars. That's the real thing that's lacking in PS... in my humble opinion *laughs*