Well VAC is enabled on the server. Whether it does anything or not at the present, I have no idea. But if it's like other game's anticheat methods, it could very well be recording the offenders for permanent ban later on down the road.
But considering all versions of the game (beta etc.) could join a server on a different version, I'd say VAC isn't doing much at the moment. And when the 1st line of code that's written every time you open that DOS box for a dedicated server says "Failed to connect to Steam client server", sadly I really don't think there's much of a system in place at the moment.
Hopefully I'm wrong
