I have received some reports that iPhoto2Gmail is not compatible with the newly released iPhoto '08. I do not have iLife '08 yet so I am currently unable to test and resolve the problem.
I'd also like to apologize to you guys for the long delay since I announced that new plugin versions would be coming soon. I tried to add too many new features and have had almost no free time to work on the plugin. I will try my best to release a new version that includes only the two most requested features -- 1)Saving Acct. Information in Keychain and 2) Autocompletion of addresses...
If I can get a copy of iLife '08 and successfully sleuth the API changes, I hope to also add iPhoto '08 compatibility. As always, these are my best guesses and I just can't promise when I will have some free time to sit down and work on building a great and stable release.
UPDATE:
Apple has released an official API and SDK. In English, that means that it should be simple to get iPhoto '08 working!
UPDATE #2: It seems several folks have had no problems with the plugin and iPhoto '08 (check out the comments)... I've purchased a copy and will try to do some testing this weekend.
UPDATE #3:
A temporary workaround was submitted by droy. If you click on the iPhoto2Gmail tab twice, it will work. I have identified the cause of the problem and it'll be fixed in the next update.