“Among the pressing issues: When should bitcoin be considered a commodity, a currency or a capital asset for tax purposes? Are bitcoin transactions similar to barter? Is bitcoin subject to the same stringent tax rules as secret offshore accounts? And how will U.S. officials keep bitcoin, which is even more anonymous than cash, from being used to promote tax evasion or money laundering? So far, the Internal Revenue Service hasn’t ruled on or addressed such issues directly. An agency spokesman released the following statement: ‘The IRS continues to study virtual currencies and intends to provide some guidance on the tax consequences’ of transactions involving them.”
http://online.wsj.com/news/articles/SB10001424052702304773104579268322915488180