Please forgive the cross-posting between this message and one over on the Narayana forums: http://community.jboss.org/en/jbosstm but I just wanted to share some information regarding these two projects.
It's no secret that the main horsepower of BlackTie comes from JBossAS, and in particular it relies upon the capabilities provided by Narayana (né JBoss Transactions).
Over the coming releases we hope to unify these two projects even further, for now you should notice a more consistent approach to documentation, website, binary distribution, code layout etc. Over time this may result in a single distribution containing both (we are looking to the community to provide the stimulus for this though).
For those of you who are not as familiar with Naryana, it provides implementations of many transaction specifications. For example, it implements JTS/JTA/Rest Transactions/WS-* transaction specifications. You can find a lot of information over on the website: http://www.jboss.org/narayana, feel free to ask questions on its forum too: http://community.jboss.org/en/jbosstm. There is even a blog you can follow: http://jbossts.blogspot.com/