Myself and other Steam gamers have been reporting troubles with downloading the demo for this game. I myself am on a Mac, but I don't know if that holds true for the others. Anyways, somebody on the Steam forums thought it might be a good idea to contact you here and see if you could talk to Steam, since they often seemingly ignore their forums. I would love to try out this game, and at $9 it seems like a steal!
Also, while I'm here, what's the iPad version about? I have an iPad and would be interested in buying the game for it, but it didn't show up on the App Store... are you still in the process of getting it approved?