Luis von Ahn sounds like the prototypical venture entrepreneur, Scott. From your posting and from a quick peek at his wikipedia biography, it appears as though is always seeking new opportunities revolving around his interests and research. His previous experience with Captcha demonstrates his ability to bring a new venture past the incubation stage and into the hands of a board of directors who can bring his technology into the mainstream.
Watching his TED talk, von Ahn is able to adeptly articulate within minutes what Duolingo can do and outlining a future vision for the company. He is an engaging and charismatic speaker and who seems like he would be a natural leader. With his background, passion and vision, I also believe that he is good role model for entrepreneurs.