We recently started inviting external speakers to talk at Digg HQ on a variety of Technical subjects. Jack Dorsey the founder of Twitter and Square stopped to talk about the growth of Twitter and the resulting engineering and cultural challenges. He talks about applying the lessons learned there to his latest venture, Square. Fascinating stuff. Interested in why Tom Conrad, the CTO of the Pandora music recommendation service, said “I need Android like I need a hole in the head”? He presented at Digg as part of the Engineer-to-Engineer: San Francisco Tech Talks to talk about how a focus on mobile applications helped transform Pandora into the enormously popular service that many of us know and love.