Capcom is apparently planning on releasing a demo for Devil May Cry which has only been confirmed for consoles for now.
A PC demo is still being discussed, as is Vergil as playable in the demo.
Joystiq picked up on the important bit of information from the Comic Convention, but unfortunately no date for the demo was given.
We got our hands-on DmC at rAge, which left us even more impressed with the reboot. You can read about our time with DmC here.