In JBoss AS7, the JBoss Web subsystem uses an internal thread pool by default. It has no exposed attributes in the AS7 management interface.
You can define a specific thread pool in the threads subsystem and associate a web connector with it (set the thread pool name in the executor property of the connector).
Thread pools in the threads subsytem can be monitored by RHQ.
Thank you Thomas for the answer!
I guess I will have to look into doing that... even though it is a hassle the default threadpool does not expose any monitoring data... maybe this is something that can be made as a change request for a possible future enhancement? I mean, this is quite important data to monitor for hanging threads etc.