The Firebug 1.0 until-recently private beta has gone public beta -- so you can download it now! We have been a select few to track this puppy throughout the last fortnight, probably drowning Joe in feedback, and it's good. It's really good. It's actually the best surgical hack tool I have been using since the age-old C64 and Amiga Action Replay(s) from Datel Electronics in the nineties, and those cheated by using specialized hardware. ;-)
And better still, the release will remain in the open source, no cost, with the Firefox style tri-license MPL/GPL/LGPL combination, having first being slated for going commercial style product with a dedicated developer hired for it, paid in full by the revenue generated from our purchases of the tool. So, in conclusion, Firebug will only get as much attention as donations can pay for, above the spare time available to Joe, recent full-time ambitious startup founder (Parakey software); quoted from the Firebug blog:
I hope we can raise enough to create a job for someone who loves building web development tools as much as I do. If not, then I would at least like to use the donations to hire an intern to help out for a while.
I would suggest you download it, try it out for a day or three, depending on how much time you have to devote to turbo-charging your development pace, improved debuggability, at-a-glance electron microscoping of the HTML, CSS and javascript you encounter in the wild as you browse about your daily life, and if you don't find it worth the $25 (or $15 if you're on a tight budget) suggested in Joe's original post, don't pay. Otherwise, please follow my lead and drop in those donations. (The karma boost alone is great! ;-)
Personally, I'm glad that the in excess of 25,000 (yes!) lines of javascript code that in part make up Firebug (there is a lot of UI graphics, and a few thousand lines of xml, xul and css too, of course) are there for us to browse and learn from, not to mention pore through, when there is some curious aspect to how things work, or you wonder about how to do something Firebug does.
The "beta" tag actually means something here; I, for one, initially encountered a suspiciously high firefox freeze frequency (several times a day) when running earlier beta versions on firefox 2, intel mac, in combination with the Stylish extension, but that mostly went away on disabling the latter extension. There are a few bugs and misfeatures left to polish away (in this case possibly not of Firebug's own fault -- it might just as well be a Stylish issue), and our feedback is still useful, hence the beta period.
Joe has unofficially hinted that version 2 will be all about configurability and extendability. Let's make that come a little sooner rather than (indefinitely) later, shall we?