I have never met Sam Altman and never seen him speak in public, but if I didn't know about YC, I surely wouldn't have known about Loopt or Sam Altman. I live in Europe and Loopt is pretty much non-existent here (all 4sq/gowalla). So why is Altman such a great entrepeneur (in terms of strategy/amibition, as stated by PG)? What is extraordinary about the things he does or has done? Why isn't someone like for instance Jack Dorsey on the list?