This particular release isn't Firefox, it's XULRunner.

XULRunner is basically the core Mozilla platform, which other apps can use to build on top of. But it *is* built using most of the same parts Firefox 3 is built on. In the future, Firefox and Thunderbird will likely be apps running on XULRunner. (They can actually be built that way today, but they won't be shipped as such.)

Brad has previously blogged about getting Firefox (well, "Minefield", as the development version is known) running on the N800.