Nothing yet, only rumors of 4g phones coming later this year or next year. It would be sweet if they could release something this year though to keep themselves in the game in that regard. Motorola, Samsung, and HTC all have 4g phones already so RIM is a little behind on this one. However, you could also say that the infrastructure isn't there yet for 4g so its not worth it to get a 4g phone yet anyways unless you live in a major city with great coverage.
Well, the other problem is the fact that BBs use compressed data. That's why the internet on those phones are like 2G speeds. 4G for a bb would still be only like 3G for other phones, but I guess anything is an improvement.