It's worth pointing out that we do not yet support the new JBossWS stack. That's on our roadmap, but is realistically a Q4 2006 or Q1 2007 goal.
We used JBoss Transactions at a successful BOF during JavaOne 2006 to demonstrate the requirements for long running transactions. There was a lot of positive feedback and a lot of people were impressed with how simple JBossTS facilitates the development of what can be a complex set of tasks. A similar presentation was given at HP World 2004 and the responses were good then, so it's nice to know we're on the right track and appear to be pleasing most of the people most of the time.
If you're interested in seeing what is possible with transactional Web Services, then I'd recommend checking out JBossTS 4.2.1 and looking at the WS-T trailmap. It's based on the well know "travel agency" example and shows how to use both traditional ACID transactions and newer compensation based transactions in the same application. As usual with JBossTS, there are a lot of details in the manuals, so check them out too.