Paul Flaherty blogs some GREAT information on a series of Webcasts for Exchange 2007.  As he mentions, these aren't ordinary webcasts - they have homework.  They sounds like a great way to get your skills updated for Exchange 2007.

Link to Carpe Diem: Flaphead.com @ Home : 24 Hours of Exchange Server 2007

Link to source website:

http://www.microsoft.com/events/series/tnexchangeserver.mspx#24HoursofExchangeServer2007