According to a NASA press release, Astronaut Mike Gernhardt will drive the rover and be accompanied by other members of the STS-126 crew. NASA goes on to say that cameras onboard the rover will record video of the parade. Later, when NASA posts that video on it's website, I'll add it here as well.
The videos below are clips from the C-SPAN and MSNBC coverage. They show the rover approach and turn toward the Presidential viewing platform. Astronaut Rex Walheim and suit engineer Barbara Romig are visible wearing spacesuits attached to the back of the rover. Rex Walheim then unattached from the rover and walked proudly with the flag in front of the new President. For closeup screenshots and the CNN coverage video, see this On Orbit post.
Both President and First Lady Obama seemed very impressed by the display, and Michelle Obama even exclaimed "wow" at one point. I wonder if this is a good omen for NASA's future under the new administration. Obama's space policy is available from his website or obamanauts.org.