There is no question there was a huge number of people at Obama's inauguration, but was there really 1.5 (or as reported in Australia) 2 million people? Anyone who has been to a large sporting event will know that 100,000 people also looks pretty damn impressive.
If it's true that the crowd was 1.5 million, it needs to have been more than 16 times larger than this crowd of 93,000.
There is a revealing statement in the last sentence about crowd counts here - namely, they are greatly influenced by political pressure.
For these reasons, and because when it comes to crowds, journalists are generally lying liars who like to lie, The ShadowLands is willing to say with confidence - bollocks
All the same, some amazing satellite photos of the inauguration here.
UPDATE: If every individual stood a loose arm's length from each other, it "is at least physically possible to pack something approaching 2 million Americans into the 2.1-mile stretch between the Capitol steps and Lincoln's feet." However, if you check the aerial photos, you will see this is not even close.
The ShadowLands says: the crowd was about 600,000.