DB abstraction summary?

["John Wells" <jb@sourceillustrated.com>]

Guys,

There're an overwhelming amount of DB libraries/frameworks/etc for Java. 
JDO, DAO, projects like Hibernate the provide O/R mappings, etc.

Has anyone ran across a resource that nicely summarizes the various
options and projects, including when you might want to use one?

If you have and could pass it along, I'd really appreciate it.  Such a
beast may not exist, but it will certainly be very helpful if it does.

Thanks!

John