Firefox 1.5.02 has been released. Just did the update and all went smooth.
http://www.mozilla.com/firefox/
Good idea to always back up your bookmarks/profile first whenever doing major updates.
Also check for updates on your themes and extensions and do those updates first and one restart before the new install.
I did an uninstall on my 1.5.0 version first and then executed the upgrade.
Here is a program you can use for backing up Firefox and/or Thunderbird.
http://mozbackup.jasnapaka.com/
Be sure you close Firefox before you do backups.
New features on 1.5.02 include:
* Universal Binary support for Mac OS X which provides native support for Macintosh with Intel Core processors. Firefox supports the enhancements to performance introduced by the new MacIntel chipsets.
* Improvements to product stability.
* Several security fixes.
* Memory fixes.