This comes from Eric Gunderson @ericg via the Mapbox blog… 
From the blog…
We’re creating the building blocks for a complete mapping stack. This extends way beyond a map. Today we closed $52.55 million in Series B financing to enable us to expand this stack, continue building amazing technology, and hire the best people in the world to do it. We’re going to grow across all teams, from engineering and data to operations and business.
This is more than just creating the best mapping platform: we embrace open source, invest in open data communities, and make a positive impact every step of the way. We’re building tools that are going to change how people move around cities, how scientists understand the planet, and how applications do anything with location.
Read also from Prolieau Advisors
Mapbox raises $52.6M led by @DFJvc to build the “Map Layer” for all apps http://t.co/ABDdSnqOEk pic.twitter.com/fLHZQQS6f4
— DFJ Venture Capital (@DFJvc) June 17, 2015