Show the list of all users who edited a node in Drupal 7
So you thought that part would be closed source ? No!
Check http://drupalcode.org/project/drupalorg.git/blob/refs/heads/7.x-3.x:/drupalorg_handbook/drupalorg_handbook.module which adds this functionality to book nodes. This module was built for drupal.org but it's not that difficult to get it modified for your needs!

If you want to do this in Views, 


Create a view with Content Revisions in under "Show". uncheck page display,check 'make a block', and click continue and edit. You will be taken to Views UI. Now, remove existing fields and add a new relationship to Content: Author. 
Add new field to user name from the just-added relationship. 
Add new contextual filter to the node ID. Set the default action to take argument from URL. Then, expand click on Query settings and enable Distinct.
Give the block a title and admin name. 
Place block where you want. 
Enjoy!