I thought it would be helpful to have a kind o' tire clearinghouse thread (if one doesn't exist already... I'm quite lazy, you know) where people can look for winter-specific tire reviews.
Right now, running Bontrager XR3 Team Issue 2.35 both front and back on a Surly Ogre SS. I'm running them tubeless (because why not?) on Stan's Crest rims, 20psi for trail duties and 30psi in town. I've been out on groomed XC ski trails, ungroomed biking and hiking trails, and taken them through deeper (>4") snow in-town. On the groomed trails, they gripped well, presenting little to no difficulty climbing- and bombing-wise. Traction was steady except on fast curves, where the rear end began to slide out ever so slightly. Cornering generally features some Tokyo drifting-style maneuvers. In deeper snow in-town, straight line traction was fairly good. Over packed ruts or through deeper banks, the rear end especially wanted to wander, but generally no complaints. The tires inspired enough confidence that I never really held back on the throttle which, I'll admit, in fairly deep snow on a 29'er SS isn't hard to do. I would recommend these for hardpack snow and snow up to ~2". Beyond that, I wouldn't recommend them for deeper snow, as the lack of cornering traction makes tight maneuvering dicey in loose conditions.
Let's hear what you're running, kids! Remember, it's for science.