Lucid Technics is happy to announce Hannibal support for S3. Hannibal generates DAOs for relational databases as well as S3. Full support for create, read, update, and delete operations. It generates S3 DAOs for your objects from the domain interface definition. Objects are stored in S3 as JSON strings.
Hannibal also comes with an S3Realm. S3Realm is an alternative to the JDBCRealm that comes with Tomcat. The only difference is that it persists your user credential information to S3 instead of a relational database.
Using Hannibal it is possible to build robust AWS cloud applications that only use S3. The next release of Hannibal shall support Lucene indexes stored in S3 as well.