Currently available books include – Introducing SQL Server 2012, Introducing Windows Server 2012, Programming Windows 8 Apps, Introducing Windows 8 for IT Professionals, Understanding Virtualization Solutions and more… Available in PDF, Mobi (Kindle) and epub, you can check them out at: –

http://blogs.msdn.com/b/microsoft_press/archive/2012/05/04/free-ebooks-great-content-from-microsoft-press-that-won-t-cost-you-a-penny.aspx