I'm going to treat bitcoins as an investment asset until things are clarified.  This means keeping track of the cost basis (BTC purchase price + fees) and subtracting the basis from the net sale (BTC sell price - fees) to calculate the capital gain.  The advantage is that capital gains held for 1 year have a lower tax rate than normal income.  CoinBase provides a CSV export for its transactions as does the Bitcoin-QT client.  If your exchange doesn't provide a paper trail, you'll need to keep your own - be sure to include the transaction identifiers so you can use the blockchain to prove when coins were purchased and sold.

Ron