It is a very tight fit - I just hope it won't prove necessary to remove it often, the only times I had to do so where when my 770 locked up solid.

To remove my N800 battery I used a craft knife to ease the battery out. Insert the blade under the lip on the battery at the opposite end to the electrical contacts, and use the side of the N800 case as a lever in order to pop the battery out by a couple of millimetres. You can then pull it out completely with your fingers.

I may think about attaching a plastic strip of plastic to the underside of the battery which will allow easier extraction in future.