Well here's a thing - a lump of in-game footage of Deus Ex: Human Revolution on Gamespot, narrated by the game's story director, Mary DeMarle. You can see it below. It demonstrates their "multi-path, multi-solution gameplay" (which was a phrase I don't think Ion Storm ever needed to use), in the game's first level. The four "pillars" are combat, stealth, social and hacking, as well they should be. Except of course "combat and stealth are the main pillars", so that's what they're showing now. So what you've got is the same level played through three times, perhaps inspired by Kieron's famous review. (And for those worried about spoilers, it's a man running from one building to another.)
This is 360 code being shown, but obviously it'll be fairly representative of the PC version. They start off showing a purely violent route, reiterating the fact that the game will never force you to be violent. Next is a rather violent interpretation of stealth. And finally a completely different path altogether.
(Gamespot's embed code is awful, so I've used this YouTube version - someone email me if it gets taken down.)