In an effort to accelerate the development of Firefox OS, Mozilla announced a Contribution Program which will aim at providing dedicated developers with access to resources and reference hardware. Foxconn will manufacture the initial reference hardware, a tablet. The program will be open to developers, localizers, testers, and bug fixers.
Twitter has open sourced their MapReduce streaming framework, called Summingbird. Available under the Apache 2 license, Summingbird is a large-scale data processing system enabling developers to uniformly execute code in either batch-mode (Hadoop/MapReduce-based) or stream-mode (Storm-based) or a combination thereof, called hybrid mode.
Azavea a company based in Philadelphia that provides products for geographical data, has published an open source product called GeoTrellis under GNU GPL v3 license which is a geographic data processing engine for high performance applications.
2011 was a busy year for OSS projects using .NET. Phil Haack has released some highlights.