yes, you should be able to use trunk on github - fixing the lack of proper tags in the master repo this week so stay tuned.
I added my hand-woven 4.0.0 tools SNAPSHOT to the hibernate3-maven-plugin and experienced the described the Ant issues. I don't think this is a use case you actually test. Why should you..once tools 4.0.0 is out the Maven plugin maintainer(s) have to take care of that. IMO there's little hope, though. Never got any feedback to the post I sent to their mailing list.
yeah, I wasn't involved in hibernate3-maven-plugin; that was all externally done and I've rarely heard from them either. I wanted them to contribute it so the maven plugin could work more or less the same as the ant tasks and eclipse integration. Just never materialized ;(
But its sure that they can't run with hibernate4 jars in a hibernate3 plugin - that will never work without changes.
About autoregistered usertypes, can you show me the code you actually want to have executed ?
We use the Usertype library to map Joda Time data types via Hibernate (it's also JSR-310 compliant). It provides several implementations of org.hibernate.integrator.spi.Integrator. The relevant abstract class is AbstractUserTypeHibernateIntegrator (autoRegisterUsertypes()). The relevant sub class that provides implementations of getUserTypes() and getCompositeUserTypes() is UserTypeJodaTimeHibernateIntegrator.
I haven't done much work with auto registered types but my understanding was that these jars just needed to be on the classpath when "starting" hibernate. Do you have these usertypes on the classpath ?
if yes, then yes we definitely need to add in a hook for this to happen and I would appreciate if you could open a issue on https://jira.jboss.org/jira/browse/JBIDE with a small example that fails for you.
Thanks!