We're still working on compiling a complete list of these changes.Firefox 3 supports new properties in the install manifest to specify localized descriptions.
See Localizing extension descriptions for more details.
So we decided to install Fire Fox 2 again on the design-machines next to an existing Fire Fox 3 installation without causing any issues with the extensions or other settings between the browsers.
I got it to work pretty much instantly on the first go, but since colleagues and friends were asking about how to get Fire Fox 2 to work with Fire Fox 3, here is a quick step-by-step guide after the break.
Quickest way to get Fire Fox 2 to work without any problems is if you grab hold of Fire Fox 2 portable.
Get it from Portable (direct link to FF2Portable) and install the application, ideally into a separate folder (such as ‘C:\Program Files\Fire Fox Portable’) Firefox 2 Portable will not allow you to open another instance of the browser by default.