So the Public Beta has finally made it, there is a ton of exciting changes. From the look of the product to the mechanics under the hood. Please download it from http://sharepoint.microsoft.com/en-us/Preview/default.aspx and give it a try in a test environment to get yourself ready for the Release to World.
As well you can find more info here about SharePoint 2013 http://blogs.msdn.com/b/vesku/archive/2012/07/17/sharepoint-2013-it-pro-and-developer-training-materials-released.aspx
And the Webcast with Steve Balmer for the announcement http://www.microsoft.com/en-us/news/presskits/office/liveevent.aspx