One of my favourite tools is the Exchange Server Deployment Assistant. The Deployment Assistant asks you some questions about your particular Exchange environment and, based on your answers, it provides a checklist with instructions that are designed to help you deploy Exchange 2010 quickly and easily. Each step has a huge amount of valuable information to guide you through your deployment.

The Exchange Team recently announced that they have updated the Deployment Assistant to include a rich coexistence scenario for organizations interested in maintaining some users on-premises with Exchange 2010 and some users hosted in the cloud by Microsoft Office 365 for enterprises. This information is only available in English at this time and requires Exchange Server 2010 Service Pack 1 (SP1).

The Exchange Server Deployment Assistant can be found here.