My host recently added GD2 so I would like to know what would be the best way to go about redoing all my thumbnails with GD2? Is there someway I can just have Coppermine take all the pictures that have been uploaded and re-thumbnail them?
Take a look at the Admin tools (resize utility) in the admin menu: you can re-create thumbnails by album with it. You can't re-create all thumbnails for the whole gallery in one go because this would cause to much load on the server's resources.
GauGau