The pretty-much-unanimous verdict (even from Greenfield's wife, apparently) is that the preplanned segment wasn't funny--and it wasn't obviously a joke. Comedy Central won't be calling him any time too soon.
And, looking for a third time at the video clip, I have to say that I doubt Greenfield's word on this: He may have meant to be sarcastic, even mean, but I don't think he was joking--distinctions usually lost on the preciously self-absorbed pundit class. Greenfield's entire segment is focused around a serious premise: he feels strongly (and clearly) that a presidential candidate shouldn't appear so hip or dress so casual, that Obama should fill Greenfield's preconceived notion of what a politician should look like.
Coat and tie are required for admission to Jeff's country club--until recently, whites-only.
It's all about context. CNN has been filling its schedule with inappropriate commentary about Obama's middle name (Hussein, for those not in the know) and last name (sounds like--well, you know), not to mention his race. The power of suggestion in this context is alone worrisome; I'd expect this type of "joking" from the clowns at the NRO's Corner. Instead of addressing the issues and the news on the so-called Situation Room, Greenfield has time to mock the way Obama dresses. (See: Pelosi, Nancy; Clinton, Hillary; et al.)
The Carpetbagger Report has the most trenchant comments on Greenfield's misfire; I suggest you read the whole thing, but I want to highlight its postscript:
Greenfield’s shot at bloggers — we feel the need “to fill all that space every day, or hour, or 15 minutes” — was cheap and unnecessary. Indeed, this little incident, if anything, demonstrates the problem isn’t with bloggers filling pages, it’s with news networks filling 24/7 airtime. Did CNN so thoroughly cover every major news story on earth on Sunday that the network had time left over for jokes about Obama’s name and clothing? Please.
Put simply, instead of commenting on the news, Greenfield created it.