I've now tried this on small scale with bitcoinplus running on 3 computers over the night. It generated a total of 0.0110132 BTC. Probably won't try it with all 40 computer as it seems to be quite a hassle.
theft is theft
What would I be stealing? Who's losing anything? As I said, the computers are used for rendering 3d graphics occasionally anyway, and then they're also using the schools render farm. So bitcoin mining is actually using less electricity than usually.
To be honest, I don't even think the IT technicians at the uni would mind. I know one of them who's involved in the Pirate Party, and pretty open to new innovative ideas. I'd be surprised if he haven't tried this himself.