The first feature complete beta for Firediff 1.0 has just landed here. This release allows for customization of the format saved by the save snapshot and diff features. Also included are some minor bug fixes and official support for Firefox 3.6 and Firebug 1.5.
This release has also been registered on Babelzilla (along with Firefocus) and any translators are welcome to provide their input.
Bugs may be filed with the fbug issue tracker.