Yes, due to the cheery activity of clever internet bods, they've managed to drag the Bioshock demo from the hands of Fileplanet before release. This caused the preloading to be cancelled and... oh, all manner of stuff. In other words, yes, it's a cheery clusterfuck.
But that's not really our problem. What matters is it's available. You can get it via a direct download via Softpedia (Which claims to be a torrent, but actually isn't) or torrent via Mininova (Which claims to be a torrent and- strike a light! - actually is). Be sure to update your drivers and stuff - in fact, the reason for the delay in the release is meant to be there's some new drivers for Bioshock coming out today, so it may actually be (er) a bit quirky.
Meer and Walker are currently excitedly downloading it, and expect some screens in the feature we're lobbing up later today.