Yes, we actually have come up with some algorithms for flagging cheaters, and then a small team of experts reviews the games in question. The algorithms are the only part of the site that is closed source at the moment; if we move over to machine learning we may open them (I think of something like Irwin).

The algorithms have been successful at catching a nontrivial number of cheaters already, most of whom have admitted it and gotten their account back after a suspension.

It is a super cool problem - I think we can catch more with machine learning (the funny thing is, my day job is in fraud detection using machine learning, so there is some overlap :)