Edit: Additional working mirror (no registration needed).
Edit #2: Nvidia has released new Forceware beta drivers (169.01) that are optimized for use with this SP demo. If you ask me it's ridiculous how you need to upgrade drivers every time a new major title is released, it happened with Bioshock, UT, and now Crysis. But anyway, pick your OS and download here.
As earlier reported, the demo will include the complete first level, dubbed “Contact,” which will give you roughly 45 minutes of gameplay. In addition, Crytek is packing in the CryEngine 2 Sandbox game editor, giving the community the opportunity to get familiar with the tools they will have at their disposal before the actual game ships on November 16.