Issues, pull requests, wiki updates, and comments are now pushed to Flowdock in addition to commits. We have been using them ourselves, and it has significantly reduced the time it takes to react to a pull request.
The configuration can be a bit of work until GitHub gets its revamped hooks admin out. If you have an existing Flowdock hook in your GitHub repo, you have to poke the GitHub API a bit.
Configuring new hooks don’t require anything special. Just follow the instructions from our help page and you’re done.