I was wondering about this myself. Totally new to this Bitcoin thing and want to be cautious...
You can't get in trouble for buying or selling them. You can get in trouble for not reporting your gains for your taxes. That being said the average trader probably won't make enough to even report taxes, or rather I assume most people will get burned and give up.
Honestly, I get the feeling a lot of childish retards are attempting to get into this thing. Oh well, but this is what I do know.