In case you missed it, Exchange 2013 SP1 was released on February 25, 2014. You can read more about the release dates and build numbers here. You can download Exchange 2013 SP1 here.  I recommend immediately applying the following hotfix to resolve a 3rd party transport agent issue as per KB2938053. Although Exchange 2013 SP1 provides several important enhancements over the previous version, the biggest news for me was that it is now compatible with Windows Server 2012 R2. Stay tuned as I show you how to integrate the Windows Server 2012 R2 ADFS role into Exchange 2013 SP1.