I've checked out the cvs repositories for hibernate-3.0 and HibernateExt but can't find a tool for exporting DDL files (something like class2ddl or java2ddl) from annotated classes. Does such a tool yet exists?

try schemaexport in combination with some of the other tools

Which schemaexport? Do you talk about org.hibernate.tool.hbm2ddl.SchemaExport ? That one only takes hbm files. Which other tools?

You can genereate the hbm files using other tools, see http://www.hibernate.org/102.html

Yes, I know. But I don't want to generate hbm files. I have an annotated class (EJB-3 Annotation-Tags) - and I want this exported to DDL.

There is currently no SchemaExport adapter for annotated classes, but this should not be too difficult to add. Either write a patch which should be relatively simple, or wait for it :)