So, it looks like the Mozilla folks have taken the initiative to block a couple of (pretty much) now default Microsoft Windows plug-ins that open up a few additional vectors for the bad guys to conduct drive-by-download attacks.
The two Firefox add-in's are the Microsoft .NET Framework Assistant and the Windows Presentation Foundation (as depicted in the screenshot of my system this evening).
Brian Krebs over at the Washington Post has a blog entry up (Mozilla Disables Microsoft's Insecure Firefox Add-on) covering more of the background on the topic and what led up to this latest Firefox response.
So, thumbs up to the Firefox team for taking the initiative here and working to protect their users. Keep up the good work.
Oh, and thanks also for the work with the new Plugin Check page. Its a great start to something thats been missing for quite some time (for mainstream users). There's still a lot of work to be done in figuring out which versions are installed (if the my screen shot below is anything to go by) and helping to manage the update process. It's something I've been calling for for quite some time now (see the whitepaper - Understanding the Web Browser Threat) - but this is real progress.