It seemed incredibly likely that Bullestorm would come and go without so much as a PC demo. That's not the case, though -- one was just released on Games for Windows Live (here) and Steam (here). Cue outlandish jokes about killing the dicks off of people!
Nick posted some tips 'n' tricks for the console demo, which should still apply to whatever it is PC gamers are getting here. I'm not one to regularly play demos, but Bulletstorm is the kind of title worth checking out in that capacity, as it's a bit of an oddball.