Since I hate it when people don't post resolutions to their thread's, I don't want to be that guy.
It's an out-of-balance tire. Don't buy tires from Walmart, it's not worth it.
The steering wheel wobble got so bad on the highway portion of my commute today that I pulled off and took surface roads instead. I was embarrassed and pissed. I stewed about it all day and jumped right into it after work. I checked the torque on every bolt that I've ever touched and I rotated the tires from front to back. The wobble is now in my ass instead of the steering wheel.
I have an appointment at the dealership to get them properly balanced on Monday. Walmart tried twice to balance them and failed. They also lost one of my center caps and my security key for the special lug nuts. They eventually found both.
There are two morals to this story. First, Walmart sucks. Second, is that whole Ahkam's Razor thing. The most simple explanation is usually right. I was ready to blame the rack, rack bushings, and even the driveshaft. In reality it was the local Walmart that we all refer to as 'The White Trash Walmart' living up to its name.