Square, the mobile payments startup from Twitter creator Jack Dorsey, revealed an impressive roster of angel investors today.

Among them: Google’s Marissa Mayer and husband and private equity executive Zachary Bogue, Foursquare and Dodgeball co-founder Dennis Crowley, Twitter co-founder Biz Stone, prolific angel investor Ron Conway, Napster creator Shawn Fanning, Digg creator Kevin Rose, Delicious creator Joshua Schachter, Personal Democracy Forum founder Andrew Rasiej, a producing director of the TV show ‘House’ Greg Yaitanes, First Round Capital, XPD founder Robin Chan and Esther Dyson.

Square offers a tiny white piece of hardware that you can plug into the audio jack of an iPhone, which lets you process credit card payments through a mobile app instead of through a machine. The vision is to allow small business owners or even friends to easily engage in transactions without paying the high upfront cost of buying machines to process payments. A video demo is embedded below.