Yes guys this is not a joke. You can now download a copy of Exchange Server 2013 and play with it as much as you like in your sandbox environments.
http://technet.microsoft.com/en-us/evalcenter/hh973395
And while you’re at it you might want to check out the new Office Customer Preview:
http://www.microsoft.com/office/preview/en
Enjoy!
Until later,
Henrik Walther