We wanted to let you know about some important changes around published documents, spreadsheets, and presentations.

In a few weeks, documents, spreadsheets and presentations that have been explicitly published outside your organization and are linked to from a public website will be crawled and indexed, which means they can appear in search results you see on Google.com and other search engines. There is no change for documents published inside your organization or shared privately.
...
If a user does not want their published Docs to be crawled, then the user must unpublish them by doing the following:

- Go to the 'Share tab'
- For documents and spreadsheets, choose 'Publish as web page'. For presentations choose 'Publish/embed'
- Click on the button that says 'Stop publishing'

For more details, please see this Help Center article: http://www.google.com/support/a/bin/answer.py?hl=en&answer=60781

This is a very exciting change as your published docs linked to from public websites will reach a much wider audience of people!