I don't think they're above overstating it, but not by 10x the actual amount. And regardless of the media's obsession with Obama, I don't think they'd all purposely join together and say, "Yeah, let's jack this number up - by 180,000 people. And let's keep it a secret amongst us kids." Perhaps they went with the number the Obama campaign gave them, assessed the crowd (without any scientific method of counting people in an open venue like that) and said, "yeah, that feels about right." And who cares if it was 150,000 or 200,000? Point is, it was a whole lot.