While I focus on bringing SharePoint on top of cloud technologies customers can use, the SharePoint engineering and product teams released SharePoint 2013 Preview, more than 1 month ago.
Preview is a marketing name for one of the Beta release we always did for our products.
The thing I am really amazed with, is that they also made available a full TechNet Resource center for IT Pros!
You definitely want to have a look at it: http://technet.microsoft.com/en-us/sharepoint/fp142366
This is GREAT, Kudos to the SharePoint Product and UA teams, this is really great (I won't name them, I'll miss some ;-) )