It was a landslide.
It's not so much that Obama won Virginia. That was pretty much expected. But the size of the victory will mean more delegates and in a race that could come down to a handful of delegates, the vote count in each state is very important. To use a sports analogy, running up the score matters.
Inside the numbers, take a look at this: Obama did much better among white voters. He got 48%. That's way more than he's been getting in many other states. He also cleaned up among church goers and African Americans and did much better with women and lower income Americans (normally Clinton's strength).
I think it's safe to say that Barack Obama is the frontrunner. That sounds good on the surface but remember Clinton is stronger (for now at least) in Ohio and Texas and with two crucial debates coming up in the next few weeks, Clinton will have a chance to reset the race. The question will be: has the Obama train already left the station?