What's that name again of the cms/theme that the Firefox website uses?

Are you sure it's open source? Silver Orange did Mozilla's website, but I'm not sure if you meant www.mozilla.com, which has a different design. Although, this site says that Silver Orange did that too.

Aaaaaaaaaaaaand none of my html went through. Excellent.
"Silver Orange" = http://www.silverorange.com/a/portfolio/mozillaorg
"this site" = http://www.ontoinfo.com/2006/09/13/current-trends-in-web-design/
Sorry about that.

I am (was) pretty sure it's opensource. Seen a couple of sites back then that used the same design. I know i didn't grab the download then because I had no use for it at the time.

Thanks for the research though =]

Are you thinking of Drupal?

Now that you mention it - it might as well be.
guess I'll start browsing their theme directory then.