Jason The and Chris Bowers (along with many others) have rightfully wondered why in the world last night's results in Indiana and North Carolina were somehow definitive even though nothing fundamentally changed. I offer you this theory: TV pundits are wedded to polling.
Right before New Hampshire, polls showed Obama winning by double digits, as did the exit polls. But Clinton pulled out a narrow popular vote victory (the two ended up with the same number of delegates from the Granite State). This shocked and rocked the media's world. It enabled her to further "shock the world" in Nevada (with a nine-point popular vote win but tie in delegates) and in turn be shocked by Obama's giant win in South Carolina, where it was his turn to vastly out perform the polling. Obama didn't get a bounce out of Super Tuesday, because lots of polls had him barely winning or more narrowly losing states like California, even though he netted about 100 more delegates than Clinton did due to his small state strategy.
After Obama's 11-state romp (which also surprised the media to a degree), he promptly lost Texas and Ohio by more than expected from the polls. Ditto in Pennsylvania. This, coupled with Rev. Wright's sad exploitation of his 15-minutes of fame led to a media narrative that Obama was in serious trouble.
But then, Obama's victory in North Carolina was akin to those during his late February winning streak (and more importantly, bigger than the polling projected by about 6 points). The real mind melter, however, was the fact that Obama only lost Indiana by about 22,000, despite being projected to lose it by about 5-10%.
Obama has in particular the mayor of Gary and Lake County party officials to thank for delaying reporting their results so that Obama could dramatically "come from behind" when all the votes had been cast hours beforehand.
So to sum up, it is the psychosis of the punditry that was masterfully manipulated by Obama and his supporters that made this end. And it was the masterful manipulation by the Clintons and their supporters (and a function of the calendar) that enabled this race to last two more months past its mathematical conclusion.
And since media narratives drive the polling questions, and in turn, their perception of the public, look for national polls (which are irrelevant because over 95 of those polled will have had their chance to vote already) to show Obama with a big lead over Clinton and McCain (which is also irrelevant because Obama and the Dems haven't even begun to lay into Mccain--or McCain and the GOP into Obama) now.
[Oh and FYI: 1.25M+ Hoosiers voted yesterday for Hillary Clinton or Barack Obama. In 2004, John Kerry received 969,000 the state of Indiana...in the general election. Meanwhile, John McCain only mustered 77% of the vote in Indiana]