EWS Managed API 2.0 Technical Preview

http://www.microsoft.com/en-us/download/details.aspx?id=30391

What's new in the EWS Managed API?

http://msdn.microsoft.com/en-us/library/jj220500(EXCHG.80).aspx

101 EWS Managed API 2.0 Code Samples

http://code.msdn.microsoft.com/Exchange-2013-101-Code-3c38582c

Exchange 2013 Preview SDK

http://msdn.microsoft.com/en-us/library/jj162981(office.15).aspx

What's new in EWS in Exchange 2013 Preview?

http://msdn.microsoft.com/en-us/library/jj190903(EXCHG.150).aspx