The first thing I was told after being handed a Motorola Droid was: "Be careful with that battery cover. It loves to come off." And, sure enough, it does.
The good news is that Bryan at The Gadgeteer has posted up a quick video showing a few quick seconds with a small flathead screwdriver can help keep that cover in place, so long as you don't mind some very minor surgery to your device. (We're not worried about it, but isn't really an official fix or anything.)
Check out video of Bryan's fix after the break, and let us know if it helps you any.