Brian is pretty much correct in his assessments.  Only correction is that frequencies are available above 1.2 Ghz.
Some links for those interested:

http://www.fcc.gov/wtb/amateur/
http://www.arrl.org/FandES/field/regulations/allocate.html
http://www.arrl.org/FandES/field/regulations/news/part97/

Bob, KA0Q

<snip> Abbreviated for brevity :)
Brian wrote:
> 
> 1.  ham radio is for non-comm use only.  You can't charge money for
> anything.
> 2.  I think encryption falls in the lines of "codes and ciphers" which is
> explicitly forbidden. 
> IIRC 2.4 Ghz is unregulated and you can do whatever you want to up
> there.  "Ham" is restricted to frequencies designated by the FCC and I
> think only goes up to 1.2 Ghz or somewhere in there.  If you're truly
> 
> -Brian