Microsoft released the public beta for SharePoint 2013.

Download SharePoint 2013 Foundation here:
http://www.microsoft.com/en-us/download/details.aspx?id=30345

Download SharePoint Server 2013 here:
http://technet.microsoft.com/en-US/evalcenter/hh973397.aspx?wt.mc_id=TEC_121_1_33

Here’s a bunch of other SharePoint 2013 content
http://www.microsoft.com/en-us/download/search.aspx?q=SharePoint%202013&p=1&r=40&t=32
…including:

  • Microsoft Office Web Apps Server Preview
  • SharePoint Designer 2013
  • Duet™ Enterprise for Microsoft SharePoint 2013 and SAP
  • Language packs
  • Architecture documents
  • Lab guides

Enjoy!