The size of the thumbnail created at upload can be manipulated with the plugin API, though I don’t know of any plugins written to do this yet. You can also overwrite the thumbnail via FTP with any size you like.
Has anyone made any progress on a thumbnail-size plug-in yet?
Thanks for the speedy reply HandySolo. I’ve been following that and several similar discussions (and have successfully implemented a couple different approaches), but really need a simple way to cycle between generating/using several different thumbnail sizes. I’ve looked into writing my own plug-in, but am unsure exactly how to hook into the thumbnail bits of wp-admin/inline_uploading.php. Any help in this regard or in finding other solutions to my problem would be greatly appreciated.