As an Exchange MVP, I'm always excited by changes in Microsoft Exchange's architecture and capabilities. And there are plenty of changes in the forthcoming Exchange 2013 you may have missed, given all the attention on Windows 8, Office 2013, and Windows Server 2012.
Here is what Exchange admins can expect from Exchange 2013, based on its preview version:
Exchange Administration Center: The EAC brings to mind the quote, "You're riding it, dude!" Yes, I cannot help but think of the line from "Finding Nemo" whenever I think of the new admin console for Exchange. But seriously, the GUI-based EMC (Exchange Management Console) and the Web-based ECP (Exchange Control Panel) are being replaced by a single Web-based UI that is, frankly, my least favorite of all the new Exchange 2013 features. I don't like Web-based consoles for administration; they always feel clunky and unfriendly. Plus, it has that Metro look, which leaves me cold. We'll see if I can get used to it.
Exchange architecture revisions: Exchange 2007 and 2010 are broken into five server roles, mainly to address performance issues like CPU performance, which would suffer if Exchange were running as one monolothic application. But Microsoft has made progress on the performance side, so Exchange 2013 has just two roles: Client Access server role and Mailbox server role. The Mailbox server role includes all the typical server components (including unified messaging), and the Client Access server role handles all the authentication, redirection, and proxy services. You can deploy Exchange 2013 with an Exchange 2010 Edge Transport server role but a 2013 Edge role is planned post-RTM.
A new managed store: The store service has been completely rewritten in managed code (C#). Although this change bodes well in terms of higher availability and resiliency, it doesn't mean the ESE (Extensible Storage Engine) database engine has been replaced with SQL, as many admins would like. Exchange 2013 continues to use ESE as the database engine. But now each database runs in its own dedicated worker process, so a hung process in one database will not cause problems in other databases. Fast Search (an add-on to SharePoint 2010) is also integrated into the managed store for improved search and indexing.
Modern public folders: Rather than just getting rid of public folders (something promised for future releases), Microsoft has embraced them once again. They are no longer managed through the separate Public Folder Management Console; instead, they are managed via the EAC. That makes them public folder mailboxes, which means they use regular mailbox databases. In turn, this means they can be made part of a database availability group for disaster recovery.
Lots o' PowerShell cmdlets: Although 13 cmdlets have been removed (many having to do with the old public folder management), Exchange 2013 brims with 187 new PowerShell cmdlets. That may not be the final tally when the final version ships next year, but it shows that command-line management tools are still growing. I wasn't kidding years back when I told everyone to learn PowerShell. It's not going away.