Independent developer Mark Atwood has been working on a MySQL interface to Amazon S3. Released under the GNU Public License, the code is compatible with version 5.1 of MySQL. Once the interface has been installed and configured with your AWS developer credentials, you can now create tables using the AWSS3 storage engine like this:
CREATE TABLE atst (s3id VARCHAR(255) NOT NULL PRIMARY KEY, s3val BLOB)) ENGINE='AWSS3' connection='awss3 bucketname aws_id aws_secret'
This is a bleeding-edge, first-cut release and, as is the case with popular open source projects, will undoubtedly evolve and mature rapidly over the coming weeks and months.
Based on Mark's S3 journal entries, the basic functionality is now in place. Each database table row is stored in an S3 object. The object's S3 key corresponds to the table's primary key (which must be of type VARCHAR). Inserts, deletes, and selects are functional.
Congratulations, Mark; this is awesome.