[X-Unix] Owner/Group changes depending on login?

[B. Kuestner]

I think the answer to your first question is, that OS X (or any  
Unixish OS) actually sees UIDs and GIDs, i. e. numbers and not file  
owners and groups. These numbers are then assigned to logins and  
groups. So if "Act 2a Project" is assigned to UID 501 and GID 123, it  
matters if the OS maps GID 123 to group admin or to group jeffrey.  
Either with Panther or with Tiger Apple introduced a new concept of  
dealing with groups: Each user is assigned his own group. Your  
experiment suggests that this change happened with Tiger, so that's  
why you see the difference.

I have no idea for the second observation that ownership feedback  
changes if you ls as root.

Björn