I got a C&D from RR and Lucasfilm a LOOONG time ago when Episode 1 hit, I was running a fileserver in a Dal.net chat room.
Needless to say things have calmed down for me quite a bit since then.
If you are serious about using a public tracker don't forget about Peer Guardian2
Phoenix Labs PeerGuardian 2
Obviously the best defense is not to use them at all, but if you must any little bit of protection helps.