Latte is a quick and dirty implementation of the Product Design Document (PDD) concept. It helps designers produce PDD automagically.
PDD, as a methodology developed and introduced to public by Felix Ding in 2009, is a new way for organizing design documents. It combines Use Cases, Flowcharts and Wireframes altogether beautifully, making the reading experience much more pleasant comparing with traditional PRD/MRD. Check out http://dingyu.me/blog/product-design-document for more information.
Latte is a open source software, fork it on Github!
The logo icon is from http://www.iconfinder.com/icondetails/49740/128/coffee_drink_food_icon.
I love Latte coffee :p