I think the general lesson here is that if it is a server-based operation that can be made more cost effective in bulk, Amazon are interested in doing it.
I assume the Heroku guys have noticed by now. Hopefully they're working on designing Amazon out.
I really want someone to make an RDS-like service for Postgres. But I don't blame people for not trying right now, I'm sure Amazon will do it eventually.
I can't quite believe Amazon has never acquired anyone, though- are there any high profile ones out there?
No one builds services like amazon. They aren't interested in bolting on someone else's idea company.