+1 Nescio.

Ok I just kick in this thread to make some things clear:
You surely know what's about "deal in stolen goods" (dunno if the word "concealment" is right, only know in french it's "recel"). Will you accept getting bitcoins if you suspect someone stole these from another account ? Maybe not, you want to stay safe legally said, since this is more punished than the stealing itself.

Short: lots of people not wanting to deal with "probably stolen" bitcoins, selling them, making the bitcoin's value drop, and so on. Then, 250 000 bitcoins robbed:
- will be worth nothing if nobody want to pay for them
- still is illegal

Mt.Gox did the right thing, Kevin is already tracked down for stealing and possible relation with system intrusion and cracking (if he really did it). It's now your turn: give the stolen bitcoins back where they belong (Mt.Gox) and be less charged, or keep them and face more charges and massive bitcoin crisis of interest and value loss.

You can't fuck around thinking you're safe because it's virtual and looked legit to you, Mt.Gox has to hand over all their logs to the authorities and they will easily go up to you. Legally, they have to hand over everything they know to the authorities, may the community like the FBI sniffing on it, or not. Mt.Gox being a registered society, they have to comply to any law of the countries involved, french because of french bank and admin, american because of technical infrastructure, and japanese because of society establishment and admin home. The point is how hard you will be hit in the end, and what impact this will have on the whole bitcoin economy. And how Bitcoin will be treated by the govs.

TL;DR: give the bitcoins back. For the community, for the future of Bitcoin and for yourself.
inb4 domain names "bitcoin.org", "mtgox.com", "tradehill.com", "sourceforge.net"... get seized by ICE (they can, TLDs managed by american societies)