Well I have an answer but it will likely only confuse you more! Internet gaming is still not technically legal in the US, but you are supposed to pay taxes on gambling winnings. So you put on your tax forms you made X amount playing online and next thing you know you get charged under the wire act for illegally placing an electronic bet!
Explains how to claim winnings on your taxes but doesn't specify internet gaming.
The SAFEST thing to do is most likely stash the amount you should have to pay in taxes away somewhere and when or if they clarify the legalities on internet gaming you will be able to pay any back taxes. Best case scenario they don't ever make you pay taxes on online gaming income during the time in which it was illegal.
Well hope that helps but there really is no cut and dry answer to online gaming income and taxes here in the States yet!