I know that there is an API for Google Data that lets you interact with Google Docs.
But if you wanted to avoid Google Docs entirely and try to build similar functionality into a Rails app, are there any existig Ruby gems that could help you to achieve some of the key features:
- collaborative editing
- revision history
On the other hand, the realtime multiuser editing of a single document that Google Docs allows might be a little too ambitious and unncessary.