I don't think this is something that will happen any time soon, but what if the IRS starts to take interest in Real Money Trade in MMOG worlds? Your posessions in game do have some sort of real-world value, and the author of the article, Julian Dibbell (who has been making real money trading in Ultima Online money for a good time now) brings up some real legal issues reguarding the IRS regulations on barter and 'other' income.

Those of you against RMT, eat your hearts out.