Great article on Disk Defragmentation :

http://blogs.msdn.com/b/e7/archive/2009/01/25/disk-defragmentation-background-and-engineering-the-windows-7-improvements.aspx

----------------

(h/t The Defrag Show : http://channel9.msdn.com/Shows/The-Defrag-Show/Defrag-Govs-Nest-Bitlocker-Qs-Win7-Defrag)