As I pointed out earlier, Adobe has just donated their action script VM to Mozilla to be used in Firefox. This is really cool. For one, the VM is supposed to provide huge performance boosts. Secondly, it will ensure that your JS code works in both Firefox...
"Tamarin project: Big news. Adobe contributes a significant amount of scripting-engine source code to Mozilla Foundation. In essence, the high-performance scripting in Adobe Flash Player 9 will soon be available in Firefox, Thunderbird, and other...