it's an exciting challenge, and i've personally been interested in mobile ever since the iphone was announced.<p>what i'm working on is a mix between a geo-twitter, digg, and yelp minus the long reviews. i think the important thing is to keep changing your business model if something isn't working. levchin is well known for that type of development cycle, and i'd say we share the same ethos when it comes to the mobile space.