User efurban made a "Gallery2 to ZenPhoto Migrator" plugin a couple of years ago. I was hoping to have a go at updating it for the current version, but the website for the plugin is down now.

Does anybody still have a copy of that plugin?

The plugin was mentioned in this thread:

http://www.zenphoto.org/support/topic.php?id=2470#post-21597

and the plugin webpage was here:

http://apps.ouwu.com/confluence/display/pb/Gallery2+to+ZenPhoto+Migrator

(Wayback machine copy of the page is at
http://replay.waybackmachine.org/20090119112426/http://apps.ouwu.com/confluence/display/pb/Gallery2+to+ZenPhoto+Migrator
but the plugin itself didn't get archived)