I have often wondered about this, as the airline I fly most frequently often likes to put my bags on an earlier flight. I fly a lot of A class (since I am a large person, and need the space), and so there is an all coach flight that leaves my connecting city earlier than my actual flight. My bag is usually on the all-coach flight, which means my bag gets to the destination about 1 1/2 hours before I do.
Was once on a non-stop flight (same airline) that was oversold. I took the bump (with all the requisite freebies) and then watched my luggage get on the plane I was just bumped from. Mentioned it to the gate agent, who didn't seem to stressed about it.
I guess it's a pattern with this particular airline.
Now, it begs the question. "What if..."