It looks like all of the pollsters have weighed in with their final polls at this point. Therefore, I'll go ahead and make the final poll-based predictions on how the delegates will be allocated according to tonight's primaries. As always, I use the Pollster.com averages to generate these estimates.
As you can see, the polls suggest that Clinton will take a net gain of 4 delegates from the Indiana primary while Obama would take 9 from his victory in North Carolina. Overall, Obama would take 5 more delegates from today's primaries than Clinton.
Of course, the polls have varied significantly in both Indiana and North Carolina and certain pollsters sometimes seem to favor particular candidates. As a result, we can also put together a best-case scenario for each candidate. Five survey firms have polled both Indiana and North Carolina during the final week of the campaign. The margins those firms give to Obama in each state are plotted below.
What is notable about this figure is that four of the five pollsters fall on a diagonal line across the scatter plot (only Insider Advantage falls off this line). This indicates that the pollsters who see Obama doing better in NC also see him doing better in IN, and vice versa. You wouldn't necessarily expect this to be the case unless these firms are using assumptions that systematically advantage one candidate in both states.
Zogby would have to be the favored pollster of Obama supporters. He is the only pollster (of these five) who projects an Obama win in Indiana and he also has Obama winning by the largest margin in North Carolina (14%). If Zogby is correct, Obama would take a net gain of about 20 pledged delegates from today's primaries. More importantly, the calls for Clinton to leave the race would likely intensify.
On the other hand, Survey USA has to be the Clinton campaign's favored pollster. They see Clinton winning by 12% in Indiana and only losing North Carolina by 5%. If this happened, Clinton would likely win two or three more delegates than Obama today.
So, what will it be? Will the results follow the Pollster.com averages and produce 5-10% margins for Clinton in Indiana and Obama in North Carolina? Will Obama or Clinton have a better day than expected, as forecast by Zogby or Survey USA? We only have a few more hours to wait.
And don't forget, I'll be live blogging this evening as the results come in. Should be interesting.
UPDATE: Check out Mark Blumenthal's excellent post on the IN and NC polls here.