Crysis 2 fans were informed in an official forum post:
We’re glad so many of you are enjoying the Xbox 360 multiplayer demo - if you haven’t tried it yet, check it out on Xbox Live. At this time, Crytek and EA are also glad to confirm that we will also be releasing a pre-launch multiplayer demo of Crysis 2 on the PC. Stay tuned for more details.
We’ll let you know when they reveal a date.