I thought they were reconsidering this?
Check it out:

U.S. Olympic medalists will have to pay taxes on their awards that could result in more than a third of their winnings going to the IRS.

Prizes awarded by the U.S. Olympic Committee (USOC) are subject to federal taxes because they count as income earned abroad. The USOC hands out $25,000 for gold medals, $15,000 for silver medals, and $10,000 for bronze. But athletes in the top tax bracket, including snowboarder Shaun White, will have to fork over 39.6 percent of their winnings.