It is not fluid user experience at all. Click and drag the scroll bar to the bottom, and keep trying to scroll down. It violates expectations. The scroll bar should be sized to the amount of data that exists, whether or not it is fully loaded/rendered.
The only thing I don't like is that the URLs seem "dirty." IE I don't like seeing kajillion digit IDs with no human meaning.
Anyone have any solutions to that?
Since those IDs are just the IDs of the tweets underneath, I don't think it has much to do with the elegance of this solution, per se.
Perhaps it would be cleaner use the Flickr approach to set URL naming: