"One good developer can do the work of three or four guys," Annerino said. "Once a company finds them, they don't let them go." We might get paid double what they do, but not 3x or 4x. Or maybe I'm not that good ;)
It doesn't necessarily just happen from taking on extra risk, either, though starting your own company is one way to do it. Personal anecdote (I'm not a 10X developer but I know a few things about a few things): I previously built CRUD apps and made $X, and I turned down a few offers this year to build CRUD apps for [6 * $X, 10 * $X]. The big thing that changed? Improvement in marketing myself and better selection of CRUD app genre. (A/B testing isn't any harder technically than building university registration systems... it is just worth orders of magnitude more revenue.)
There is a really good post on Quora about this, incidentally: http://www.quora.com/10X-Engineers/Why-are-the-best-programm...