I work for a large company, large enough that I see people I don't recognize on our campus every single day.
Two years ago this weekend (Presidents Day, which is a holiday at our office) we had an enterprising thief roll a cart around our office around 5 PM on Friday, loading up laptops. Of course, by then most everyone had skipped out for their long weekend, but if someone was in the office he'd tell them it was for the "weekend virus scanner upgrade", promising people that their machines would be back on Tuesday morning.
I don't know this part for a fact -- our security people and management don't talk about this at all -- but I've heard it enough that I believe it: When someone objected to having their laptop taken, he'd act irritated and ask why they "didn't reply to any of the emails about the upgrade" and then make a show of updating his clipboard -- he'd collect the asset tag from the machine, office number and actually get the person to sign on the line.
I have no idea how many machines he made off with, but it was enough that we all had to suffer new BS security procedures for a year afterword. I would imagine that you could do this at pretty much any big office and get away with it.