How to disable thumbs.db files?

bobwild is not correct.

thumbs.db will be created in any directory connected to by osx. This is created for faster loading by finder and the files are automatically hidden. This includes external media and fileservers. When viewing the same directory in another operating system they are no longer hidden.

To disable the creation of such files on connected media, the following command must be entered into terminal.

defaults write com.apple.desktopservices DSDontWriteNetworkStores true

you must log out or restart to take effect.

thumbs.db files are microsoft Windows files. You can delete them. There is nothing to disable in OS X LION.