Mozilla has issued alpha versions of its Firefox Mobile browser, better known as Fennec, for Nokia N900 and Android powered smartphones. Fennec for Android works on Android 2.0 or later and requires 30MB of available internal storage. There are both ARMv7 and ARMv5 CPU optimized builds available. Also, expect some bugs to occur, since its an alpha build.
You can download the Fennec alpha by accessing Firefox.com/m/alpha on your Android or Nokia N900 handset.