.DS_Store files can make even the tidiest network shares look horrible to none-OS X users.
Whenever an OS X machine accesses a network share, it creates a .DS_Store file for it’s own use (on SMB/CIFS, AFP, NFS, and WebDAV servers). These files are invisible to the OS X user, but will show up to anyone else using other operating systems such as Windows or a Linux distribution.
Turning them off is easy though, by running the following command:
defaults write com.apple.desktopservices DSDontWriteNetworkStores true
You will need to either log off or restart the computer for the changes to take affect.
For more information, please see the official knowledge base article here: http://support.apple.com/kb/HT1629