Not sure if topic is related to JBoss Transactions. But...
I saw some JBoss webinar about intention to create connectiors.
So far as I know there are limited number of vendors for mainframe adapters: iWay Software, BEA (Tuxedo),NetManage, Pervasive, CONNX Solutions, NEON Systems, Software AG, Micro Focus, Data Power.
Guess it may help
Staff I am developing a project for a great company in brazil... and to know if they know some connector java to speak with mainframe