First Read has some thoughts about why Obama might agree to those joint forums McCain has proposed, the most important being this one, I think: "It cuts out the media and the commission from the debate/forum conversation -- something campaigns hate. They like to have their own control and simply force the media to cover them roadblock style." That would be a big selling point, particularly after the disastrous Gibson/Stephanopoulos debate last month. On the other hand, would the joint forums necessarily preclude more traditional debates? Maybe, but I'm not so sure.
The MSNBC folks also had an interesting take on SNL's latest Hillary sketch: "[A]nyone else sense that SNL -- which was pretty tough on Obama early on -- is trying TOO hard to win over Obama folks with that cheap-shot filled parody?" I also thought it was a little crass. Though I'm not sure it was a conscious make-up call so much as SNL doing what SNL does, which is drive a truck through any comic opening. Those Obama-and-the-media sketches from earlier this year weren't exactly subtle. (Funny, yes, but not subtle.)
Update: Here's that video.