The Exchange Server team announce the released of enhanced Exchange Server Deployment Assistant that include support for configuring rich coexistence (also known as "hybrid deployment") for organizations interested in maintaining some users on-premises with Exchange 2010 and some users hosted in the cloud by Office 365 for enterprises.
This scenario is in addition to the existing support for configuring rich coexistence between on-premises Exchange 2003 and Exchange 2007 organizations and Office 365.
"The new coexistence information for the Exchange 2010 environment is only available in English at this time and requires that your existing Exchange 2010 servers are updated to Exchange Server 2010 Service Pack 1," the team said.
"Rich coexistence ("hybrid deployment") offers organizations the ability to extend the feature-rich experience and administrative control they've with their existing on-premises Exchange organization to the cloud. It provides the seamless look and feel of a single Exchange organization between an on-premises organization and a cloud-based organization. In addition, coexistence can serve as an intermediate step to moving completely to a cloud-based Exchange organization. This approach is different than the simple Exchange migration (aka cutover migration) and staged Exchange migration options currently offered by Office 365 outlined in Email Migration Overview in Exchange Online help," explained the team.
More Info: Exchange Server Deployment Assistant
[Source: Exchange Team Blog]