So far, so good. It doesn't seem to have the memory leakage I was seeing with Firefox 2 on Windows XP. I've gone on and upgraded to Firefox 3 at work as well, on my desktop and on my Macbook Pro laptop.
For the Ubuntu systems I'll probably just want for upgrading to the current versions of Ubuntu so that all of the libraries are in place, etc.
On the Mac laptops, I'll ask the familiy owners about adding it to them. The Macs should probably come next.