Happens to me as well. Only on "downhill" grades though. (So if outdoors which is very uneven, it's pretty much constant.) Last patch fixed the name bouncing but the character still does.

I've found that if you limit your FPS via FRAPS or any other method to about 30, it stops or becomes hardly noticeable. (But why play like this?) Based on my research I've come to the conclusion the problem plagues higher-end systems, as people with mediocre ones don't experience it. (Which relates into limiting the FPS)

Running on HD5850, Intel i5-750, Win 7 x64

Screen tearing is another thing, Had to use D3DOverrider to force on V-sync since it's not built in... but like I said that's another thing lol.