Update: Since Exchange 2013 has now been released the preview forums has been retired, and the RTM forums can now be found here.
Since the Exchange 2013 Preview is now available it is a great chance to see how the next version of Exchange is shaping up! If you are running to issues then head on over to the TechNet forum for Exchange 2013 Preview and see if the community can help out.
In addition the Exchange 2013 Preview help files are also available for download. That way you don't have to watch movies on those long haul flights, now you can read chum files