BlogThis, the original Firefox Extension for Blogger, doesn't work with Firefox v2.0
On Phil Ringnalda's blog there's an article about the BlogThis Firefox Extension.
There's also a comment that explains how to update the BlogThis extension so that it works with Firefox v2.0
I've done the update as per the explanation, and installed the BlogThis extension successfully in Firefox v18.104.22.168
Here's the modified extension...