if one has the energy/anger to go to all the trouble of placing bait, doing a steak-out and beating some random dude up, it seems to me there is a better option:

set up the bait, do the steak-out, take pictures of the guy breaking the lock, stalk the thief (carefully) to wherever he goes, then call the cops with the street address. i know a lot of us hate the fuzz, but -- as BostonFixed pointed out -- legitimate revenge can be a lot more effective than angry punches to the face.