As reported in my updated WordPress 2.6 features list, support for Google Gears in the administrative back-end has been added to the WordPress Trunk (i.e. the current development version).
According to the development ticket for the Google Gears patch:
The patch adds all static files used in the admin interface to a single offline storage. That speeds up page loading a lot, as it serves virtually all requests for static files from the computer’s HD instead of the network. So instead of 50-60 requests to the server on some pages, there are only 2-3.
Personally, I’m waiting for the WordPress 2.6 demo to be updated with a supporting alpha version so I can try Google Gears out. I just certainly hope it turns out to be more reliable than some other Google Gears implementations have been.