"... Could someone tell me more about this Jason Calacanis fellow. ..."
If you listen to others explain who Calcanis is you'll get what people think he is. Instead listen to this interview (and read the show notes), on Stack Overflow podcast, "Podcast #56 Jeff Atwood" ~ http://blog.stackoverflow.com/2009/06/podcast-56/
He came across as smart, funny and determined. It's his determination that struck me the most.