This is a neat trick. If you're one of those bleeding edge people who want to try out Firefox 3 while it's still undergoing major changes, but don't want the hassle involved in installing, uninstalling, and repeating daily, this script could be a major time saver.

The nifty script downloads the nightly build and installs it as a portable configuration, allowing you to keep the use of your trusty mainline Firefox, and still play around with the nightly build like the cool kids.