Exchange 2013 is already available MSDN subscribers can download the available. However, it is not yet possible to migrate from earlier Exchange versions. Service Pack 3 for Exchange 2010 and an update rollup for Exchange 2007 SP3 (announced for the first quarter of 2013) are still missing. A direct migration from Exchange 2003 will not be possible. Microsoft is therefore remaining true to its "two versions backwards compatibility". An inplace update from earlier Exchange versions is not possible.
Server 2008 R2 and Windows Server 2012 are supported as operating systems. It is not possible to install Exchange 2013 on core servers without a graphical user interface. As with Exchange 2010 and Exchange 2007, installation on domain controllers is not supported.
Server 2003 is still sufficient as the overall structure functional level, so the domain controllers may continue to be operated with Windows Server 2003 SP2.
Outlook is supported from version 2007. There is no longer support for Outlook 2003. There is also no longer support for Entourage 2004 and Entourage 2008 on the MAC.
Here is a list with supported web browsers for Outlook Web App (OWA). Microsoft supports Windows Phone 7 and Windows Phone 8 for ActiveSync. Other manufacturers such as Blackberry, Apple (iOS) or Google (Android) will certainly support Exchange 2013 soon. I have already been able to successfully synchronize an iPhone with iOS 5 and iOS 6 with Exchange 2013.
What's new in Exchange 2013?
- Reduction of Exchange roles to mailbox and client access, elimination of the hub transport role (was integrated into the mailbox role)
- Elimination of the public folder database, public folders are now stored in public mailboxes
- No more Exchange Management Console, administration now via Exchange Administration Center (EAS) or via Powershell
- Built-in anti-malware protection (viruses and spyware)
- Data Loss Prevention: http://technet.microsoft.com/en-us/library/jj150527(v=exchg.150)
- Better integration in Lync and SharePoint
A complete list of the changes can be found here: http://technet.microsoft.com/en-us/library/jj150540(v=exchg.150)
