Kevin Rose has announced the release of the new Digg Firefox 3 extension. Video demo above.
The key features: where ever you are, Digg will follow you:
Notifications: No matter where you are on the web, you can discover popular Digg stories and stay up to date on what your friends are Digging, submitting and commenting. These notifications are fully customizable. Within your preferences you can track different categories and media types, and turn notifications on or off.
I haven't installed it yet, but it also promises the ability to Digg stories from the toolbar, a handy feature, but something you can get from other plugins (note though, if it allows you to do it without hitting Digg, then +1 as a feature). One for the Digg fans.