Desktop permission changes

Question

I would like some help regarding permissions. In our office, each employee uses their own iMac and we are on a small Ethernet network. There are four iMacs and each is running Snow Leopard. I have configured it so that each iMac is sharing its desktop. In our office workflow, my co-workers and I intuitively share files by dropping them onto each other's desktops.No need to hunt in our drop boxes which are buried a few levels.
ISSUE: When I put a file onto a co-worker's desktop, the file permission changes to 'nobody'. If they continue to work on the file and try to save it, they can't. So in order to continue working on a file they have to 'Get Info' first and change the permissions to 'Read & Write' for themselves. However, if I ask my co-worker to get the file from my desktop, the file's permissions are fine and they can open, modified, and save the file without a problem.
QUESTION: Is there a way to configure our settings so that files can be put onto the desktop's of other co-workers without having to mess with the permissions each time? Why does it work one way (get) but not the other way (put)?

Answer 1

You don't have permissions to modify an item you do not own.  When you copy a file to another account, it keeps your ownership and permissions, which means only you can write to it.  When another user copies your files, they own the copies, which lets them write to it (you might not have noticed, but you won't have permission to write to their copies, either).
You can use ACL (Access Control List) entries to give additional permissions - each user's Drop Box folder is also set up this way.