On the fence regarding Warhawk? Can't decide whether to pony up and buy the thing or wait for a demo so you can sample it first? Sorry. You might be waiting a while. Like, forever. SCEA have told Gamedaily:
Warhawk was designed to support up to 32-players online simultaneously. In a demo version of a multiplayer only game, there is little control over how many players will be on a dedicated server at a time, potentially leading to smaller online battles that do not fully do justice to the title's fast combat and frantic play.
That's a definite no, then. When Can We Expect a Warhawk Demo? [Gamedaily.biz]