Firebug 1.4.0 was released today. I've been running alpha and beta versions for what seems like forever now. Things have been shaky, but they've gotten a lot better lately. There's a ton of changes. This release is recommended for all users and it looks like everybody will be upgraded soon to this new release. Great job dev team. I know 1.5a is going to be in full focus now with more great stuff. Firebug is also becoming a platform to build addons on. I keep seeing more and more addons built on top of firebug. I guess I should do a separate post with some great Firebug addons.
See the full announcement here: http://blog.getfirebug.com/?p=295