This is Mozilla's first shot at the mobile browser market. With Fennec's first alpha release, they are just trying to get feedback about the current user interface of the browser with some nice features taken from Firefox like the smart URL bar, tabbed browsing, touchscreen support, popup blocker to name a few.
Nokia N810 is the only supported device for the time being but if you're still interested to give it a try then there's a simulator for users running Windows, Mac OS X or Linux operating systems.