the problem w/ detecting cheaters is that its hard to make the server very aware of whats going on... we dont have the time or resources to make it aware of game data, which makes coding MP even harder.
As far as just detecting max speeds, this is still difficult, as you know VC is pretty glitchy. For example, if you glitched through a wall and resulted in a teleport, it would be an unfortunate reason to get banned from a server for speedhacks / teleporting. etc...
We are looking into methods though, but the truth of the matter is, the best way to stop cheaters is to put more things server side. We are working towards this, but its difficult given the nature of the project.
Kent