All three Triple Crown races will return to NBC beginning in 2011, along with pre-race coverage on NBC's sister channel, Versus. The past few years, the Belmont Stakes has been on the ABC/ESPN family of networks.
BloodHorse.com has an article outlining the new deal (Link). A piece at CNBC also discusses the details (Link).
While ESPN is certainly the most well-known name in sports TV, it's pretty clear that the network isn't going to devote a ton of resources to the Triple Crown and/or horse racing. Pre-race/undercard coverage has been severely cut over the last few years, and where at one time the network televised the Oaks and Black-Eyed Susan day cards, today it doesn't even broadcast from the tracks on the day before the main events.
While it remains to be seen what kind of coverage the new NBC/Versus deals provides to racing fans, the mere fact that the deal includes pre and post-race coverage, along with the Oaks and the Black-Eyed Susan, is a step in the right direction. Additionally, Versus doesn't have a ton of huge events to compete with racing for time. Obviously, the network centers its current coverage around the NHL, but the schedule is not nearly as crowded as ESPN's. And more racing on TV can't be a bad thing, if done right.