The GPG guys are reading the forums, but are focusing their efforts on the game right now. Servo has posted a few times but mostly they're leaving it to our guys (such as me) who aren't directly involved in the work going on, so it doesn't get slowed down.
Kryo, Zargon, and Frogboy all do a fantastic job of funneling information for us both ways. On average they are able to devote more time to intensely watching their forums and IRC, and especially for time-critical testing or communication, more often than not, we choose to have them post on our behalf than to do it ourselves here, because they are diligent shepherds.
We do have forums of our own, as has been pointed out above, and we have some very insightful SupCom/TA people who help us isolate complex scripting and engine bugs. BUT we point our fans here for general Demigod communication because neither we nor Stardock want to present a multi-headed Hydra to the average user, as the above mentioned Cerberus is quite sufficient for the task.
The unusual part of the relationship, from our past experience is that Stardock is the active developer for the internet-based multiplayer matchmaking component, whereas on other GPG projects we either handled that in-house (GPGNet), or subcontracted externally (Zone, GameSpy, etc.). Because that is getting the lion's share of the attention right now, we need to let Stardock handle that relationship.
I hope that helps answer the question.