I notice it seems to be more robust when it comes to updating the photos that it shows. Before, in 2.1, I would sometimes have to restart the gallery a few times before it would show recently added photos. The gallery in 2.2 seems to get them on the first try.
On a side note, the camera is a HUGE improvement. Not only does it have a much nicer user interface and improved features, but it just takes better pictures (part of that, I think, is the simple fact that it is faster).
-SR-