I'm not aware of it being illegal per-se, ie criminal. But there is some rather strong evidence that volunteers for a for profit company, if treated like an employee (time cards, minimum work hours, training, etc.) would probably be able to successfully sue for back wages and penalties.
In February 2010, the United States for the Southern District of New York gave preliminary approval to a settlement between AOL and the Community Leaders totaling 15 million dollars. Final approval was granted in May 2010.
(Good luck to the OP, I know that situation can be rough)
It's basically a PITA for corporate taxes for a company to accept free work that contributes to their bottom line, as well as the AOL case noted elsewhere.
http://en.wikipedia.org/wiki/AOL_Community_Leader_Program
In February 2010, the United States for the Southern District of New York gave preliminary approval to a settlement between AOL and the Community Leaders totaling 15 million dollars. Final approval was granted in May 2010.
(Good luck to the OP, I know that situation can be rough)