Exchange Server 2013 Service Pack 1 Coming in Early 2014

The Microsoft Exchange Server team has announced the upcoming availability of Service Pack 1 for Exchange Server 2013, scheduled for release in “early 2014″.
Service Pack 1 will include:

• Windows 2012 R2 Support
• S/MIME support for OWA
• Edge Transport Role

More details to be released once the Service Pack release date is confirmed.
The Exchange team also said that Service Pack 1 is essentially CU4. Considering we are at CU2 right now that leaves open the question of when CU3 will be released. The Exchange Team Blog – Source