Mac OSX creates .DS_Store files on network mapped folders to store metadata (such as position of icons, added comments on files and folders, etc.). On a local (Mac-formatted) disk, these are stored as filesystem metadata, but on network folders, this is not possible, so this data is stored in a file instead. While this file is hidden for Mac-users, Windows-users will immediately spot the file in each folder that's accessed by a Mac. The creation of these metadata files can be turned off for network shares on SMB/CIFS, AFP, NFS, and WebDAV servers.

Open a Terminal, and run the following command:

defaults write com.apple.desktopservices DSDontWriteNetworkStores true

This is a user setting so it has to be run for each user on a Mac. Also, note that this will prevent the use of Mac's more advanced features such as adding file metadata on network shares.