Organic groups Node Approval module adds functionality for group members to approve or reject nodes. This is an arbitrary voting / recommendation method that isn't tied to a specific functionality. It also integrates with Flag to indicate the global state of the node. You can use Views to display lists of node states or lists of user states.
Per client request the UI for this module is "different" than the standard acceptable UI for Drupal modules. It is generally accepted that when you create a module that extends functionality of nodes, users, etc... that the settings and UI for that functionality exist on their own page (callbacks). Specifically most developers use MENU_LOCAL_TASK. Og Node Approval puts user state info directly on the node and injects a custom comment form into the node display. It has not been abstracted out to its own module yet.
- Rules, Action, and/or Trigger support
- Develop an API for user and node status changes