Let's get the bad news out of the way first. Surefire doesn't' make cheap stuff. This thing is going to cost you about as much as your first car. Unless your first car was a rusted-out, VW Rabbit with 200k miles and a rack and pinion that worked best on right turns. If that was the case, then this light will cost more than your first car.
The good news is that the light allows identification of objects up to 1km away, useful for border or maritime work. The Arclight uses arc light technology, usually found in stadium lighting, to make a light that puts out 1600-2800 lumens for about an hour using 16 CR123a batts or an integrated rechargeable battery, respectively.
The HID lamp has no filament to break, matching the durability of the hard-anodized aluminum body nicely. The three pound light is about the size of a double D cell flashlight with an '80 VW Rabbit CV joint boot on the front. It will be available in the middle of 2009. Expect a soul-searing 5000 lumen version, the Arclight 3, to follow once Surefire's engineers regain use of their melted retinas.