From an Engadget article it appears that making copies of 360 games is now a real possibility. The hack involves taking a part your DVD burner so you can switch disks without ejecting. Considering dual layer DVDs are now under $2.00, making backups of your games might be worthwhile.
Of course you also need to do a fairly complicated firmware hack so your backups will boot.
In some ways this actually makes me want to have an Xbox 360. There is something very satisfying about modifying hardware to do things it wasn’t intended for. However, the only new system I’ll be buying this year is the Nintendo Wii.