There's been a lot of buzz lately about Surly's new beast, the Krampus. Pushing the limits of what a 29er mountain bike can be, it is built around new 50mm single wall rims and 3" tires. They are calling this 29+, as it is built around the 700c rim diameter used on 29ers. Up until now, 29er tires were maxing out in the 2.5" range and, according word on the internet, that was due to limitations on tire molds. Not sure how Surly worked around this, but it could open the door to a lot more fat rubber for 29ers.
Regardless, like all thing Surly the frame is steel and the prices are reasonable. Prototypes are being ridden now and frame/fork/rim/tires should be available soon.
I don't have any pictures and I'm not going to steal any, but you can check out pix from Maurice over at Dirt Rag who gives his first impression here.