You can get v 0.10 from the archives:
http://notoptimal.net/iphoto2gmail/archive/iPhoto2Gmail_v0.10.pkg.zip
Unfortunately, changes in Google's contact code means you will likely
not see any of your contacts. The rest of the plugin should still
work. I apologize, but the move to 10.4 or greater was necessary to
continue to support contacts.
JI