The Seam transaction API is an abstraction over JTA. It provides the same interface, but can accommodate a different providers underneath.

For instance, you should be able to adapt it to any single resource transaction (recognizing that you lose multiple resource enlistment) (similar to what spring does: http://www.infoq.com/articles/spring-modules-jcr). The module could even go a step further and provide simplified transaction configuration for JTA in a standalone environment. I think there is a lot of interesting avenues to explore, which is why having it in a separate module makes a ton of sense. The floor is open for discussion.

-Dan