Google Docs: How to backup periodically?

This was covered on Lifehacker:

Back up your Google Apps data

If you've jumped on the online word processing and spreadsheets bandwagon, you've probably already got a lot of docs on Google's servers (I know I do). By default, backing up those files means you'd need to download them one at a time, which is quite frankly a tedious waste of time.

Instead, Firefox users can back up all or select chunks of Google Docs and Spreadsheet files in various formats (including MS Office or Open Office formats, PDF, plain text, or CSV) in one fell swoop using the Google Docs Download Greasemonkey script. This solution requires a little diligence on your part (you'll need to regularly back up the docs yourself), but the Google Docs Download script makes the process fairly painless.

Google Docs Backup from Google Enterprise Marketplace

It seems the only way to do this is with Documents (text docs) only, not spreadsheets or presentations. You can select them all, then choose More Actions > Export as > Save as HTML (Zipped)...:

There is a Python script where you can choose output format. It simply downloads ans converts you documents and puts them in a directory.