I first went to the Bluetooth menu, selected Setup new device, it found my mouse, and I went to connect. It then asked for a PIN. I had no idea what it was asking, so I clicked cancel. Then I noticed there were settings for device type and PIN, unfortunately this time, no matter what I did, it wouldn't display the mouse under devices. I then went under the Bluetooth menu again, and saw that the mouse was listed, so I selected Connect. It again asked for the PIN. This time, I entered "0000" as was listed for Mice under the PIN settings in the Bluetooth setup window. It didn't work. And now it wont connect, recognize the mouse as a new device, or let me do anything with it.
Sorry, that should be Ubuntu 11.10.