Well this is an environment-friendly administration so he will have to be mass-transit guy, whether he likes it or not.
I wouldn't call him the token republican though. He is from Illinois, so maybe Obama picked him because he actually knows him and feels he's the most qualified for the job. He's actually the third republican Obama has picked (the other two are Gates and Jim Ramstad as the Director of the Office of National Drug Control policy). Ramstad btw was a terrible choice (IMO always).
The only cabinet secretary that hasn't been announced yet is the Secretary of Labor. The favorite appears to be Mary Beth Maxwell (who would be the second lesbian in the administration after Nancy Sutley), but I have a feeling Obama will come up with someone totally out of leftfield.