The United States Supreme court declined to hear a case involving a man that telecommutes from his Nashville home for a company based in New York. This leaves a lower court ruling intact that allows New York to fully tax 100% of the man’s salary.
Essentially, this ruling puts telecommuters that work for out of state companies at risk of taxation by multiple states. Currently only New York, New Jersey, Pennsylvania, and Nebraska have laws allowing this kind of taxation, but other states may pass similar laws to increase revenue. All is not lost, however, Congress is looking at a new law, the Telecommuter Tax Fairness Act, that may prohibit double taxation on telecommuters.
An article at CNET News goes into further details on the subject. Senators Dodd and Lieberman along with Representative Shay sponsored the Telecommuter Tax Fairness Act which is currently stuck in committee.