Rated 5 out of 5 stars
@wendymr - You're a bit of an idiot really. Actually drop the 'bit' part.
It says it is currently compatible up to 3.0a1 which is the first ALPHA release of Thunderbird 3 and was a while ago now. You get an alpha release then beta then RC (release candidate) then the final release.
If any of you moaning idiots had actually bothered to click the link to te official page for this extension you would see that it clearly says, in large letters:
"Due to lack of time I do not have Thunderbird 3 compatible version yet, but I plan to make a version. As December is a busy month I can not promise a version this month, but please check this site later to see if a Thunderbird 3 compatible version is available."