I started an article on Disk performance and characteristics for the PFE Performance Wiki a while back. I had actually forgotten about it (those who know me know my memory is Swiss Cheese sometimes). Anyway, here is a link to the article:
http://social.technet.microsoft.com/wiki/contents/articles/disk-in-depth-pfe-performance-guide.aspx
If you are a disk expert, feel free to critique and/or update 
Cheers,
jeff
That information about SAN vendors disabling the inner part of the platter is interesting. Thanks!