"Thus far, only 2 networks (ABC and FOX) have jumped on board Apple's $0.99 rental model for individual TV episodes. Meanwhile, executives from both Warner Brothers and NBC Universal have explained that the low price point for individual episodes is not something they're willing to get behind out of fear that it undermines the quality of their content."
CBS is more on the fence about it than Viacom is, saying "let's see how this works out," but with the recent removal of Jeff Zucker as CEO of NBC, perhaps they might rethink their position at NBC and be the third network in the stable. Once the other networks see how well (or how bad) this deal is for their networks, it may change things up a bit. Seems kind of funny though, when the networks will allow streaming via Netflix but not via iTunes. According to this Ars Technica story, the networks get a flat rate and no viewer metrics (such as how many times watched, etc) from Netflix and that is ok, but to get a percentage of sales and also get some metrics isn't ok? I would think they would be able to utilize the information they can get from iTunes and it would be a benefit. But it matters not as long as you aren't totally committed to Apple products and nothing else. There are still lots of options out there, namely Hulu, Netflix and Boxee.