From this article . Letterman is setting it up so that each studio or network can make their own deal with the WGA to get the writers back to work. Apparently, this cuts out AMPTP from the bargaining table.
Letterman = genius?
I don’t think it’s all Letterman’s idea. The WGA had that option already, and I suspect that they’d have been wanting to try it out around now anyway. Of course, the fact htat Letterman’s ready and eager to deal gives them a lot of good press and steals a bit of the AMPTP’s thunder.
The bad news, though, is that the big players in the AMPTP seem to still be showing solidarity, saying that they won’t cut deals that aren’t approved by the AMPTP negotiators. 
Even CBS was (were?) quick to disown Letterman’s plan to cut a deal, even though they stand to benefit a lot from having his new material on their network, because it might have looked like they were getting around the studio hardliner’s solidarity.
Personally, I think that CBS inc would be really smart to cut a deal themselves. They’re a small fish in terms of the other AMPTP corporations, and not diversified. Their only real business is the television network. The strike will hit them hard, and it’s even possible that one of the other corps (like Time Warner,) will take advantage of any opportunity to buy them out. But there’s no sign of them seeing sense so far.
sigh