This is rumor only, but we may hear more pretty soon.
Gration would be an interesting choice. He's not terribly connected with NASA (in 1982 he served as a White House Fellow with NASA's then-deputy administrator Hans Mark), but his military career is impressive. Interestingly, there are rumors abounding (though with precious little evidence) that Obama wants NASA to cooperate more freely with the Department of Defense to speed up a return to the Moon and/or fill the gap after the Shuttle era but before Constellation flies... in fact, some people say he wants to scrap Constellation and go with military rockets after the Shuttle. All of these are rumors which I have been hearing, but all we're getting is hearsay and unnamed sources. Take these with a grain of salt.
I will say that not having experience with NASA can go either way... I was not terribly happy with Sean O'Keefe when he was top banana at NASA, because he seemed far more concerned about budget than about actually exploring space. Dan Goldin had prior NASA experience, but his "faster better cheaper" plan may have led to troubles internally and externally as management of missions slipped and some probes were lost.
Anyway, because Gration is at the rumor stage, I won't comment more on him specifically, but you can read more about him on his wikipedia page.