
It's not a V bottom, it's not a U bottom, it's a Nike swoosh recovery - Greg McLenon, Hotovec Pomeranz
MOZILLA FIREFOX versions 2.X and 3.0, as well as other Mozilla software products, are named in two critical security advisories issued Wednesday.
Mozilla Foundation Security Advisory 2008-34 applies to both Firefox versions plus Thunderbird and Seamonkey.
Mozilla Foundation Security Advisory 2008-35 applies to both Firefox versions.
Firefox 2.X reportedly updates automatically if the user has left update checking enabled. However, it's reported that automatic updates are disabled in Firefox 3.0, so users must download and install the updated Firefox 3.0.1 manually.
Firefox 3.0.1 is available for download here. µ
The packaged version of FF3 in Ubuntu 8.04 doesn't auto-update and can't be selected to, but Ubuntu's system update serves that role - have to wait for the hotfix to trickle through though and it hasn't yet...
I looked in options and I have updates enabled. But when I click help and look at "check for updates" it is greyed out.

Firefox still hasn't prompted me to update yet...
I have installed firefox 3.0 (upgrading from either the beta of version 2) on 2 XP machines, and no automatic update has happened yet (it's enabled).
Got FF3.0 on two computers here and both automatically install the new update.
I updated from FF2.x to FF3.0 the day 3.0 came out and it auto updated itself to 3.01 no problem the other night.

So I assume you mean a first time user who installs FF3.0 will find auto update is disabled?
My FF3 has just told me this update is available.
Firefox 3 does actually prompt the user to update to v3.0.1 . . . 

See here:
http://www.flickr.com/photos/28773304@N08/2678497530/
My 3.01 updated automatically, so I'm not sure what the issue is.
That's funny I have version 3.0.1 and I didn't download it. It automagically appeared on my computer when I started working today.
Don't download the whole thing again. Just go to Help -> Check for updates, and Ffox will find the 3.01 update
I didn't have to download the update manually, and I haven't changed any settings. In fact, it didn't even ask me if i wanted to install it like 2.x used to, it just installed it next time i started the browser.
"However, it's reported that automatic updates are disabled in Firefox 3.0"

Whoever reported that got it very wrong!
My Firefox 3.0 automatically updated to FF 3.01. Your comment re: FF 3.0 not able to update automatically should be checked.

Q
No problems found here - move along.

Both V2 and V3 have automagically upgraded themselves without any manual intervention. 
You can go to help -> check for updates and get it semi-automatically. No need to download from the site.
Um... My updated last night automatically. A little impatient?
Automatic updates in Firefox 3.0 works just fine. It updated automatically to version 3.0.1.
No worries, be happy.