I am glad to not play in groups that award "roleplaying" XP at all. I consider games that have explicitely written how to award advancement points for "roleplaying" to be inferior and making the game experience poorer for everybody. That was so in The Dark Eye 3rd edition, and it's still so in Shadowrun. The players can roleplay and have fun as much as they want. Also, there is even less logical reasons why a character who acts like the player (the one guy or gal who created the character by the way, you know?) wanted anyway suddenly gets better when he gains a level-up, just for being himself.
The only way roleplaying XP-awards could be justified would be if the GM handed out prepared character-sheets with detailled behaviours of the character to the players, and the players have to act "correctly". Only then would judging "roleplay" performance make sense.
But such games I wouldn't even touch with a ten-foot pole. If one really wants to perform before an audience, learning to be a stage-actor or making a movie would be a far sensible choice.
I am glad to know that D&D 4th edition will not support the dumb idea of "roleplaying XP"-awards.