With Exchange Server 2013 and Exchange Online in Office 365 for Enterprises, customers continue to have the flexibility of moving to the cloud on their terms – whether switching fully to the cloud via a cut-over migration, migrating over time with a staged migration, or managing mailboxes both on-premises and online with a hybrid Exchange deployment. This unique hybrid option allows customers to move to the cloud at their own pace, while leveraging the sharing of calendar free/busy information, hosting mailbox archives in the cloud with Exchange Online Archiving, and enabling users in both organizations to connect and work seamlessly with each other.
Read these two great blog posts on the MSExchangetam blog:
Until later,
Henrik Walther