Just uploaded new version of the Firebug Net Panel History Overlay. The new version is 0.2.1. It adds support for Firefox 3.0.* and adds new menu item Clear History.
I don't know why the addon's main page is not showing the latest version but the file can be downloaded from here, and source code from here. As with the previous version login is required since the addon is in the sandbox. Talking about sandbox, some review/feedback would be highly appreciated so I can nominate it for becoming public. Thanks.

**Update**
The public page of the add on has been updated, seems there is a bit of lag between uploading new version and showing on the site, none the less all links should work.