These are the published FAA regulations for recreational RC use (and yes, that includes those of us in the industry who do not fly for commercial purposes (I may be paraphrasing a bit here)):
1. The aircraft is flown strictly for hobby or recreational purposes.
2. The aircraft is operated in accordance with the community guidelines and within the nationwide community based program.
3. 55lb max weight, unless certified
4. Aircraft operates in a manner that doesn't interfere with manned aircraft.
5. If flown within 5 miles of an airport, be in communication with the tower about doing so, or have pre-established mutual agreements with the tower when in a permanent zone.
You can find the complete set of laws in section 336 of P.L. 112-95:
http://www.gpo.gov/fdsys/pkg/PLAW-112publ95/pdf/PLAW-112publ95.pdf
So basically, business as usual for us hobbyists.