I've always wondered why all whitepapers I'd read sucked so bad. Now that I'm in the process of writing one -- not even long, five pages -- I think I know why. You're trying to say stuff that techies will like as a quick overview while also aiming at PHBs that think it's all there is to know about your technology. And it has to sound like serious information while pushing the marketing as far as possible. In other words, you can't get it right, and mine will suck even though it's on cool tech.