from th eerror it doesnt look like a HornetQ issue, but tbh ive no idea. have you tried using the HornetQ jms bridge?
To my knowledge there was nothing special done in any previous version of JBoss AS to support the sun-jms-adapter JCA RA. I would expect it to work in AS 7 given the proper configuration. Have you used the rar-info tool from IronJacamar to generate the necessary XML for your standalone.xml?
I can't really speak to the configuration of the bridge on WebLogic, but as Andy said the error doesn't look related to HornetQ (mainly because HornetQ doesn't use JBoss Remoting). It appears related to JNDI.
Although Andy suggested using the HornetQ bridge, this is only available in the AS 7 nightlies. Documentation on how to configure the bridge is available here.