Appengine ? Edit: Appengine Datastore offers the ACID properties that simpledb lacks, is hosted and massively scalable. It offers a subset of sql, and also all

Appengine ? Edit: Appengine Datastore offers the ACID properties that simpledb lacks, is hosted and massively scalable. It offers a subset of sql, and also allows to forget all sysadmin/dba stuff. It fits all the requirements of the OP