I would like to consider implementing collaborative editing for nodes. This would work similarly to collaborative editing in Google Docs, polling the server about every 30 seconds to get the changes that other users have made. I am relatively new to Drupal, but I do not see any reason this would not be feasible. Would it be useful to anyone? Seems like it could be a fun, challenging, project.
Collaborative editing would make it easier for people in remote locations to collaborate on content creation in a Drupal environment. It could increase the user friendliness of Drupal by easing the editing of content.
3 Months (Google Summer of Code)
I will personally implement the project. It will be distributed through the Drupal Organization and Google (with Summer of Code)
Funded by Google Summer of Code

Comments
Great idea
I'd love to see this. As someone who uses google docs constantly, I think it would be awesome to bring more features into Drupal. My particular interest in this is in terms of project management. Most groups use google docs for project management (list servs, docs, spreadsheets, etc) but I think Drupal is a better place to do that.
a reference
Maybe you want to take a look at past proposes about this in SoC:
Excellent idea. The
Excellent idea.
The implementation would be key though. A lot will already be expected as benchmarks for this have been set quiet high by Google Docs. But if collaborative contribution on Drupal, like this, does become possible, I know of many organizations that would jump onto Drupal's badnwagon. Reason being that although Google Docs is great, organizations would love to keep information within their firewalls.