Michael,
I just went through the presos, and asked a few of the presentors on this. I found where it mentions that the CM can be deployed in the server farms as it doesn't perform any optimizations of traffic. I don't think it HAS to be deployed in the server farms however and as a matter of fact, the CM can be deployed anywhere that has IP connectivity with the rest of the WAEs it's managing.
However, one benefit of doing that would be that the CM traffic to the edges could be optmized with TFO optimization.
Hope that helps,
Dan