Rated 4 out of 5 stars

With a small modification, i was able to get it to work on thunderbird 3.
Simply download the file and open it with Winrar and look into the install.rdf
Look for the point 2.0.0.* and replace the 2 simply with a 3 and it will work on TB3 :)

This review is for a previous version of the add-on (0.9.1).