GT, I love you man. I appreciate your ability to throw vendor bias out the window in favor of real critical reasoning. Ah, refreshing.
In any event, an overlapping channel is an odd idea, though I agree that the net effect would be as desired. As Jafar (the villain in Disney's Aladdin) says, "desperate times calls for desperate measures." Directional antennas are definitely the way to go here. I do agree that the real problem at WWDC was over-utilization and network saturation, plain and simple. I also went into the "what would I have done" question thinking about infrastructure control with SLAs and rate limits and such (as is obvious from my blog), but you and others make the good point that a lot of the contention comes from attendees rebroadcasting their own Wi-Fi and not necessarily from the WWDC-provided network. In that case, there's little that can be done by an infrastructure to control this. I would love to have a filtered capture of just management traffic from the conference. I bet this accounts for an enormous percentage of the overall utilization.
In any event, this stumble should provide Apple with sufficient motivation to make the next model 5 GHz capable. The fact that this discussion hasn't yielded a solution that is good for everyone is proof enough that Wi-Fi is limited by virtue of unlicensed frequency...and 2.4 GHz is just too dang crowded. 5 GHz support should be standard these days, and people should have a choice between crap performance (2.4 GHz) and poor battery life (5 GHz) when the dichotomy is present. But let us choose, please.