Some information regarding what when to expect:
- General availability is planned for Q1 2013;
- Those on Office 365 Enterprise can expect their service to be updated as of November;
- Exchange 2013 will become available through Volume Licensing and for TechNet or MSDN subscriptions as well mid-November;
- Exchange 2010 SP3, required for co-existence with Exchange 2013, is still scheduled for first half of 2013;
- Still no word on when to expect the Rollup for Exchange 2007 for co-existence.
For those interested in the changes, consult the Changes in Exchange 2013 or MEC 2012 Summary posts. Note that information contained in these articles may be subject to change while their based on the pre-RTM product.
Note that also Lync Server 2013, Sharepoint 2013 and Office 2013 went RTM. More information on that here.