The microsoft exchange Team has released two architecture diagrams pertaining to the exchange 2010 hub transport Server. These diagrams are useful to anyone supporting or architecting Exchange 2010 since they reveal components of the Hub Server which aren't revealed using the Exchange Management Shell.
Looking at the diagrams you'll understand much more about queues, how RMS/IRM fits into mail flow and a few other bits which may surprise.
If you've ever wondered how things look under the hood, then here's your chance to find out:
Well done and thank you to the Technical Writing Team.