It would be nice if there were a official Maven Plugin for Hibernate Tools.
I wrote one with support for hbm2java and hbm2ddl using the JDBCMetaDataConfiguration for now.
You can find it here: https://github.com/stadler/hibernate-tools-maven-plugin

Instead of brewing my own little plugin I think it would be better to have an official plugin that can also profit from the latest developments of hibernate-tools.
You could use my plugin as it uses the same license (lgpl) as hibernate tools.
What do you think?