Categorize, label or organize GitHub pull requests?

Question

Is there a way to organize pull requests on GitHub? For a big project with lots of contributors and pull requests, it seems like it would be invaluable for admins to at least be

Answer 1

Note (April 2014): in the blog post "L is for Labels", GitHub announce the possibility to easily edit a label on existing issue with the l hotkey:

That would apply to pull request as well, in its conversation tab.