Watching from the sidelines I have to say that Obama's actually looking pretty distant and unscathed. He invited him to say a silly prayer and suddenly everybody dug up a crap load of dirt on the guy. I've never really liked him, he's always seemed pretty smarmy but managed to stay above the fray. Walking out before Dan Dennett came around to compliment his book and pretending he was a reasonable member of society. Obama clearly can't rescind the offer, so you couldn't blame him considering all the new stuff we're learning.
Warren changed the language on his webpage to make it less gay-unfriendly (failure to delay gay satisfactions until after death means you no get into church), and Obama more of a commitment to the gay community on his transition site (which is certainly a more honest step).
But largely, I think this is all pretty positive. Obama comes off a little naive but stuck and Warren gets to writhe in the flames of public opinion.