Best practices are patterns that have proven themselves over and over again as a way to achieve a high quality of your solutions, and it’s completely irrelevant who proposed them.
SharePoint should never be installed on any drive other than C:. For ULS logs, they should be on a separate LUN if performance is required (as should the BlobCache and IIS logs). ULS and BlobCache paths must be consistent across the farm.
Well not fully convinced but check point 3 at, which really is loud and clear
http://technet.microsoft.com/en-us/library/cc850692.aspx
I do know 110% that Logs and OS should be on different drives!
As for SharePoint I am really not sure. As Brian said, it doesn’t really grow, so it doesn’t endanger the stability of the system by risking the C:\ drive to get full.
I am really curious to see other opinions!
