I actually think this is a task better suited as a layer for the interim. As per their new features last week, Amazon is clearly focused on the really hard stuff. What they should probably be announcing next is a guarantee of S3 and EC2 placement within a specific data center. Then things get really interesting. Maybe Amazon could integrate this project in their services at some point... but for now, it seems best on its own.
Re: "What they should probably be announcing next is a guarantee of S3 and EC2 placement within a specific data center. Then things get really interesting."
This appears to be what their new 'availability zones' feature provides.
The availability zones do guarantee EC2 placement within specific data centers, but from what I've heard, do not guarantee S3 placement. Because so many web services are tightly coupled with EC2 and S3, this presents a dilemma. If I'm wrong though, please correct.
Also, how well does SCALR actually work?