I must admit, I quite liked the Firdbird name (or Phoenix, which was arguably better still, was it not for legal issues). Apparently the Firebird database community strongly objected to the codename, so the browser had to undergo another renaming procedure, which is a real shame. Still, as Shovel says, it'll all be Mozilla Browser some day soon when everything merges, which should finally put an end to all the confusion.
The improvements of Firefox 0.8 over Firebird 0.7 are roughly as follows:
Windows Installer - No more .zip files (includes a new XPInstall frontend, in comparison to other Mozilla-based products).
Download Manager - Improved version, accessible via 'Tools > Downloads' or Ctrl+E.
Improved 'Add Bookmark' Dialogue - So as to allow the creation of new bookmark folders without using the Bookmark Manager.
Work Offline - Now available without the need for an extention, although whether it will be as good as other browsers' offline modes remains to be seen.
Improved Binary File Handling - Media and archive files, say, are now downloaded rather than being outputted as garbled text in the browser.
The dialog that appears when installing themes and extensions has been redesigned and is easier to use.
New default pinstripe theme for MacOS X
Lots of bug fixes and improvements, including disabling form auto-completion is now functionng, the address bar now remembers the edited text across tab switching (yay!), among many other bug fixes.
I'm really liking this release so far There are a lot of nice GUI enhancements and general bug fixes (including, thankfully, the bug which wiped any altered contents in the address bar upon switching tabs).
1) install, tell it to install to your APPLICATION DIRECTORY by hitting cancel
2) close firefox as it says
3) load up [firefox dir]/chrome/installed-chrome.txt
4) scroll down to the bottom, and look for
5) change that to tabestensionsBindings, save, and restart the browser.
As Scooba highlights, some extentions and themes will not be compatible with Firefox 0.8. This will apparently be the case until around release 1.0. Sometimes they're easy enough to fix, other times you'll have to wait for the authors to update whatever it is you're after.