Exchange Server 2010 includes a new unified platform for both high availability and site resilience that is very different from the high availability model and solutions provided in previous versions. Exchange 2010 includes significant changes at its core that integrate high availability deep in its architecture, making it even less costly and easier to deploy and maintain than previous versions of Exchange.
Please download the attached video and watch it full-screen. It's just over 5 minutes, and it will familiarize you with the concepts and process for configuring highly available mailbox databases. Part 2 is coming later this week.
Please click on the video thumbnail below to see the video. There is a Download link where you can download the video (Right-click, Save Target As...):