The Facebook and OpenSocial meetup last night was a nice networking event and the organizers hosted a presenter of one of the most popular (#5) Facebook apps. The topic spanned across various aspects of the Facebook application development and specific features of Green Patch. That included user self-expresssion, ability to obtain credit for caring for someone's patch, and its eco-friendly motif with regards to helping the environment and help in case of the natural disasters. David King, who is the main author of the app, gave audience a perspective on the evolution of the app and how end users steered the original features and designed towards what the site is today. There are over 5mln users of the app which is pretty cool. He also addressed some of the technical aspects of the application with regards to its architecture and technology utilized. It includes PHP, MemchacheD, MySQL, LightHTTPD ("lighty"), and the app is deployed on Amazon EC2 cloud with some usage of S3 for image caching.