Stratosphere Hackathon
Stratosphere is an Open-Source system (https://www.stratosphere.eu), allowing you to do analytics beyond MapReduce. It features a programming model that generalizes MapReduce with multiple additional concepts, and a powerful parallel dataflow engine. The system solves many shortcomings of common MapReduce engines, like Hadoop, and gives in many cases a cleaner and more efficient approach to parallel data processing.
Please find more information and register at https://2011.berlinbuzzwords.de/wiki/stratosphere-hackathon.