Hi!
I just wanted to let you know that the db4objects dev team (developer.db4o.com) just added support to make your object model persistent with only one click from Eclipse:
developer.db4o.com/blogs/product_news/archive/2009/05/18/automagically-enable-db4o-transparent-persistence-for-java-via-eclipse.aspx
Also, if you're new with object databases and db4o you might want to check the "Getting started with db4o on Eclipse" video available here:
developer.db4o.com/blogs/community/archive/2009/05/21/second-getting-started-with-db4o-video-java.aspx
Enjoy!!