Here is an interesting update that seems to be drawing a little heat from the Web at large. Depending on your Internet settings (from Control Panel > Internet Options) you might have issues with some downloads being blocked.
Here is what Mozilla has to say about the issue.
Starting in Firefox 3, downloads of executable files (e.g., .exe or .msi) may fail and the Firefox Downloads window will contain this message, under the filename: This download has been blocked by your Security Zone Policy.
This issue occurs because Firefox 3 now honors your Windows security settings for downloading applications and other potentially unsafe files from the Internet.
The rage here is that the Internet Options you see from the Control Panel links back to Internet Explorer 7. So in a round about wacky way, Firefox 3 follows IE7′s security settings. Need a fix?
To change the setting, open Internet Options (via Control Panel or from Internet Explorer -> Tools) and click the Security tab. With the Internet zone icon highlighted, click the Custom level… button. A list of security settings for the Internet zone will appear. Find the “Launching applications and unsafe files” setting (under Miscellaneous) and select “Prompt (recommended)”.
If that does not do the trick for you, there are a few more fix suggestions on Mozillazine.org you can try. So are you upset about this or could you care less?
We are always talking about adding features to Firefox, what about for those people who would like to take them away? Better yet, how about adding features that let you take other features away? Ok, now I am even confusing myself. 
Well, this is one of those security issues that everybody always knew was there – but the community usually did a good job at policing it themselves to where it did not become an issue. It looks like somebody has been creating and uploading Greasemonkey scripts that steal your cookies. Since your cookies store a lot of information about you – you can see this is a kind of big deal here.
Need Help? Be sure to check out the 
Hey I see you, walking down the street – keeping your eye on me. Don’t think that I am not on to your little tricks, because I know exactly what you are doing. You are tracking me aren’t you?
Extensions that auto-update? Yeah, there could be a threat there and we aren’t sure when a fix is coming.
I say this is good news! 
