What if PC theives were allowed to steal from NPCs, but then automatically the NPC offers a quest to PCs (not the theif) to retrieve his stolen items/money?
The PCs would have to chase down each other, and one PC would have to find the other PC, take him to a court, and show proof that he was the theif.
This could be coded as an automatic thing, with a set type and amount of evidence to retrieve and present to a court system of NPCs.
Of course, with the release of CB will come player and NPC descriptions, so NPCs can be coded to decribe the player based on his/her description or Avatar.
When the quest is solved the theif himself is either put behind bars (if he loses) for a period of time (longer if the theif spent the money/sold the items he stole) OR let to go free and keep the loot (if he wins).
Naturally, skillfull theives will then try not to leave evidence by hiding from NPCs, and then obviously skilled theives would also try not to allow themselves to be suspected.
There, that\'s my $0.02