Gates explains Longhorn changes
ZDNet interview with Bill Gates on Longhorn.
Robert Scoble has posted a load of related blogosphere links on the Longhorn news.
Also, see Chris Sells' What WinFX on Down-Level Windows Means for Developers - article describes how bringing WinFX to Windows XP and Windows 2003 affects developers and how they should apply themselves to WinFX using the resources provided by the Longhorn Developer Center.