Multiplexing multiple building blocks over the same JChannel/PullPushAdapter

It should be possible to layer multiple building blocks (e.g. 2 DistributedHashtables, 1 NotificationBus etc) on top of the same JChannel or PullPushAdapter.
1) Investigate whether multiple state transfers screw up the digest
2) PullPushAdapter as an MBean
3) 1 Message input queue per building block ? If multiple building blocks are layered on top of
the same PPA, they will all share the same dispatcher thread. If one BB takes a long time to process the
message, all others are blocked too. If we have multiple queues, then they are independent