In fact, the only difference that a regular Firefox user will notice between this alpha and the current shipping version of Firefox 2.0 is that the top browser title bar and the About screens use the Firefox 3.0 code name Gran Paradiso instead of Firefox.
But while this alpha release has no interface changes, there are some fairly important changes in the underlying engine of the browser. Gran Paradiso is also an alpha of Gecko 1.9, the forthcoming rendering engine for Mozilla browsers.
One of the bigger changes in the release is that the engine now uses the Cairo library for all vector graphics rendering. Gran Paradiso also includes changes to improve page rendering and performance, and on Mac OS X it now uses the Cocoa application environment, which will make its Mac versions easier to develop.
In our tests of Gran Paradiso, we didnt run into any problems with sites and it worked well with the small set of graphics tests we ran it through. Mozilla said it is hoping that site developers will run this alpha through their applications in order to find problems early in the browser development cycle.
One of the biggest changes we found in this Firefox 3.0 alpha is that fact that it will only run on Windows 2000 and later and on Mac OS X 10.3.9 or later, which, while still much better than IE 7.0s operating system support, will affect users of older operating systems who want to use the latest Firefox browser.
Firefox 3.0 isnt expected to ship for at least a year, but developers who want to start testing with this early alpha can download Gran Paradiso.