I’m just getting into this whole bitcoin thing. It seems to me already, though, that getting great results from bitcoin mining would require a server farm, super computer, etc; worrying about individuals taking advantage of their GPUs or crypto accelerators is probably pointless. What can 30000 khash/s really get you? Maybe around the equivalent of $1.50 per day at current difficulty levels? Not really a very efficient means of recouping the cost of an expensive gaming rig.
I’d be much more concerned about what somebody with a botnet might be capable of.