Amazon SimpleDB -- released last week that provides access to a scalable storage of structured data via a REST API, which runs along side with EC2 and S3 to provide the "scalable backend" for online applications. Comments over the weekend have ranged from "it sucks" to "who needs Oracle/MSSQL/DB2?". I personally won't be using it. It won't scale down as much as FOSS DBs like MySQL or PostgreSQL which are virutally free with your shared hosting. It "might" scale up (which has not yet been proved), but it will soon become very expensive. 10GB/domain is a big show-stopper, latency sucks for database-intensive applications, query time limited to 5 seconds, and no inter-domain queries. Sounds like it's no good for any serious RDBMS-replacement work. It will also force you to code your applications specifically for that platform, just like S3. Vendor lock-in anyone?