Scott Hanselman has a great post on junctions in Windows Vista. Scott mentioned that he was seeing different behavior from David Mohundro surrounding the Documents and Settings folder. I ran my own tests and this is what I came up with.
C:\>dir /ad
Volume in drive C has no label.
Volume Serial Number is 6053-B050
Directory of C:\
09/16/2006 01:38 AM <DIR> $Recycle.Bin
09/05/2006 06:12 PM <DIR> Boot
09/22/2006 12:59 AM <DIR> dnn
08/29/2006 05:35 PM <JUNCTION> Documents and Settings [C:\Users]
09/05/2006 06:13 PM <DIR> MSOCache
09/26/2006 06:25 AM <DIR> Program Files
09/20/2006 02:46 PM <DIR> ProgramData
09/29/2006 03:41 AM <DIR> System Volume Information
09/05/2006 06:00 PM <DIR> Users
09/17/2006 09:06 AM <DIR> utils
09/23/2006 04:50 PM <DIR> Windows
0 File(s) 0 bytes
11 Dir(s) 8,475,971,584 bytes free
So I'm seeing "C:\Documents and Settings" as a junction pointing to the new C:\Users. Makes Sense, but a directory listing on Documents and Settings didn't return anything.
C:\Documents and Settings>dir /a
Volume in drive C has no label.
Volume Serial Number is 6053-B050
Directory of C:\Documents and Settings
File Not Found
However, I was able to change to "C:\Documents and Settings\rob", and it behaved as expected, showing the same contents as C:\Users\rob. Looking further, when I double click Documents and Settings in explorer I get an "Access denied" message. Looking at the folder permissions gave the answer, Documents and Settings has a special permission setting of Deny Everyone for "List folder / read data".