I am really shocked at how many people seem to get lost on Obama's ability to convert moderate conservatives.
Alot of people at DU are familiar with George Lakoff's indispensable 2004 booklet, "Don't Think of an Elephant." He talked at length about the liberal dilemma about having the facts on our sides without the least use. You could couple it with "What's the Matter With Kansas?" as must reads of the last Presidential cycle.
Lakoff's big idea was thinking about politics through framing, which has to do with the way the brain (in American culture, I'd add) processes campaign information through various filters. It is a great read and I highly recommend it (rather than explain the whole thing).
In any case, Obama's appeal to moderates and conservatives essentially answers the questions posed by both books (neither of which provides nearly sufficient answers to the problems they bring up).
In a nutshell, Obama instinctively knows how to frame liberal issues to the American public in a way that the Clintons never could.
During the 90's (and well beyond), they chose to make up the difference by throwing away some of the key issues in the progressive agenda like media consolidation and a social safety net. They also chose to dissocociate themselves from the term "liberal," thus legitimizing the efforts of the vast right wing conspiracy to make it a dirty word (which it remains to this day).
I won't even go into what effect this has had on Hillary Clinton's foreign policy posture.
Despite his impressive - in the fullest sense of the word - ability to make moderates and conservatives walk away nodding their head, Obama has not sacrificed a progressive agend in the process. He simply knows how to frame progressive ideas in a way that makes them common sense.
Alot of people around here deride him for this accomplishment, but it remains a key part of Obama's appeal for me. Not only does he have rock solid plans for health care and energy reform, but he can really drum up the public support for the issue and get it passed through Congress.