"A few more OpenGL cheats with increasingly greater ban penalties for repeated detections."
"We're not going to list the actual cheats VAC will/won't detect, since there are many cheat developers and cheaters subscribed to these mailing lists. We'll continue working through the active cheats and will update VAC as
often as we can."
These updates only apply to Counter-Strike and Day of Defeat servers. Do not worry about downloading anything, the servers should update themselves.
Links: Valve