GDataCopier is a free and open source project that provides a command-line tool called gdoc-cp that allows system administrators to automate bi-directional copy of documents and spreadsheets between local machines and Google document servers.
GDataCopier also presents Python programmers with an API to incorporate document/spreadsheet download and import features into their applications.
Warning: GDataCopier is known to have issues with Google accounts that have never been used before, please ensure you have used your Google account via the web interface at least once.