Homepage - http://www.mozilla.org/products/firefox/
I couldn't find it on the homepage, so I have provded a direct download link. It is from the Mozilla website
A recently disclosed vulnerability in the Firefox 3.5 web browser forced the Mozilla Firefox development team to release version 3.5.1 of the web browser early to fix the vulnerability. The vulnerability, which is affecting all operating systems that Firefox can be installed on, is linked to the Firefox JavaScript Tracemonkey engine. A temporary fix was published soon after that would disable part of the Javascript engine.
The Mozilla Firefox team is currently distributing the Firefox 3.5.1 update to all mirror websites. It is expected to be announced publicly in the next 48 hours giving Firefox 3.5 users a change to update their web browser to fix the security vulnerability.
on firefox website still 3.5 version
yeap is up now on the site.
Just a heads up, Firefox 3.5.2 is being released on august 3rd.