This module has been a long time in the making - the initial commit of the basic functionality was added about 6 months ago when I had just finished working on a JDO based app running on Google App Engine. The module was inspired by the tapestry-jpa module at Tynamo.
JDO as a standard is a curious beast. It was the first attempt at building solid ORM functionality for the Java platform, there were a bunch of solid implementations out there (Apache JDO, Kodo, etc); however, it somehow never managed to catch fire like Hibernate. For a while, at least for me, it felt like the standard was on its way out, giving way to JPA; yet, it keeps coming back: Google App Engine JDO support, MongoDB JDO API through DataNucleus, etc.