The Exchange team blog posted a great article on the features available with different versions of Outlook when coupled with different versions of Exchange on the back end. One of the cool features when using Outlook and Exchange 2007 is enhanced Out of Office Assistant. You have the option to customize and turn off or on Out of Office messages for those inside your organization and those outside your organization. Very nice. You also have a number of rich text formatting options available so you can pepper those messages with all kinds of business essential eye candy.