Either I'm using Firefox less often (IE8 rules!!!) or Mozilla are updating Firefox more often than I remember! I spotted that 3.0.9 had come out and thought I'd update Firefox on my work laptop only to discover that I still had 3.0.7 installed! I therefore had to install 3.0.8 before restarting and then checking for 3.0.9. You'd think they could release some sort of cumulative update to ease the pain. To prove I'm not a total Microsoft fanboi I must point out that at least I didn't have to restart Windows afterwards.
EDIT: Firefox 3.0.10 is now out!
It fixes a bug they introduced when they "fixed" 3.0.9. This is precisely why Microsoft take time to test things properly before they release a patch, to try and avoid regressions.