From DJ's site

Braindump: NoDsStore

Prevent Creation of .DS_Store on Network Shares

• Open terminal
• Run command: defaults write com.apple.desktopservices DSDontWriteNetworkStores true
• Restart or log out and back in

See: http://support.apple.com/kb/HT1629

If you want to get rid of your existing .DS_Store files run find /path/to/the/share -name .DS_Store -delete.

Do anything written here on your own risk.