Well, some German researchers claim they've solved the mystery.
Their vote is for a meteor.
Elmar Buchner and Thomas Kenkmann say the key to their finding was tiny grains of "shocked quartz" -- basically, quartz that has a different microscopic structure from normal quartz due to undergoing extreme pressure of some sort -- that was created by the impact.
Now, while Canyonlands officials have raised the possibility that a meteor created the dome, which is in the Island in the Sky District, they've also said erosion has washed away any evidence of such a cataclysmic impact. The two Germans, though, say they found the quartz grains off to the side of the crater, not in the middle, a finding that suggests the meteor collided at an angle.
You can find a story about their findings at Discovery News.
Now, if you want to see Upheaval Dome in person, head to the Island in the Sky District, and once there head to the aptly named Upheaval Dome Overlook Trail. It's a short (roughly 1 mile to the first overlook), easy hike. And after you've viewed the dome, take the kids to play atop Whale Rock, from which you also can view the dome.