I was having the same problem as described in this thread: http://talk.maemo.org/showthread.php?p=634544
The solution:
I had Username field in sharing plugin configuration set to username @ ourdomain.com. It didn't work. I have changed it to username from the Picasa public gallery URL: http://picasaweb.google.com/username. Now it works.

Great that you found a solution and reason for the issue. Seems like a bug. I don't have google hosted domain so never noticed this before. I will need to look into this.