I cannot see pictures on http://your wordpress Blog]/gallery.php, but all the links are there and I can click on them.
Answer: Probably one of these would solve the problem:
-. Disable mod_rewrite plugin on G2. This due to either the API provided by G2 doesn't support this yet or Perl mod_rewrite module got confuse? (mod_rewriting WP URL then mod_rewriting G2 ?).
-. Fix the configuration. Make sure you did installation step no.5.
Does this plugin support multiple users?
Not for now. I do this on my spare time, aside from job, girls, and watching too much anime. Right now, I'm just focusing on look and feel and front-end usability. Beside G2 is still in beta and there is always issues about security.
How can I tell if it's working?
You should see G2 panel under Admin->Manage->Gallery Tab
You should see G2 under http://your WordPress Blog]/gallery.php