I read about popbeans in Carol Deppe's book The Resilient Gardener. The specific one she mentions is a garbanzo, Hannan Popbean. She writes that she discussed the selection process in her previous book (on breeding veg varieties), and that she expected to release Hannan Popbean in fall 2010 at Fertile Valley Seeds. But the website hasn't been updated so you'll have to email her.
http://www.caroldeppe.com/fertileval.../fvsindex.html
added: I see that nunas are an entirely different kind of bean and require short daylength. It's astounding that they're available only in the Andes!
http://www.nap.edu/openbook.php?record_id=1398&page=177