oh yeah...miniFM

The only unlicensed operation that is permitted on the AM and FM broadcast bands is covered under Part 15 of the FCC's rules, and is limited to a coverage radius of approximately 200 feet. (See the Commission's July 24, 1991 Public Notice.) Unlicensed operation is also not permitted in the television bands (including 87.9 MHz, which falls within the 82.0 to 88.0 Channel 6 television band). Fines and/or criminal prosecution may result from illegal operation of an unlicensed station."
http://www.fcc.gov/fcc-bin/audio/howtoapply.html

If you dig a little deeper its easy to find the following document which clearly states that any FM broadcast under 0.01 microwatts (a radiated diameter of 200 feet) is ok.
http://www.fcc.gov/mb/audio/decdoc/scandoc/910724/1.jpg

"Presently, the maximum penalty for operating an unlicensed or "pirate" broadcast station (one which is not permitted under Part 15 or is not a Carrier Current Station) is set at $10,000 for a single violation or a single day of operation, up to a total maximum amount of $75,000."

-this was taken from fm.thing.net