I am pretty sure I have prior art on this. Take a look at this project I published back in 2000, though it was written in 1998 on Freshmeat:
It implements a REST interface, with Triggers that are used to create replicated servers of itself. It had a large deployment at SCO (yeah, chuckle...) and MySQL back as early as 2001. MySQL used it as the object store behind its Worklog system (and I think worklog which is published on Sourceforge still has hooks for it). Someone would need to ask Matt Wagner when he originally made use of it for MySQL. I'd have to search my email to find the name of the guy who ran the mod_repository cluster at SCO.
Want to hear the funny bit to this? I took the concept and wrote a module for Slashdot call Slash::Repository (or some such). I think it is running on SlashCode, and might even be backing Slashdot right now. It handles replication via MySQL. It was powering document storage on Newsforge.com and Linux.com at one point.
I find it hard to believe that I am the only person who has prior art on this patent. When I came up with the idea of mod_repository I didn't find it very revolutionary when I invented it, and I still don't think of it being that now.
None of this is meant to knock what Amazon has done, I think its pretty impressive. I am a big fan of what they are doing with AWS.
It is not new or inventive in nature though.