NASA announced an International Space Apps Challenge planned for 2012:

Demonstrating its commitment to the Open Government Partnership, NASA will work with space agencies around the world to coordinate an International Space Apps Challenge to be held in 2012 that will encourage scientists and concerned citizens from all seven continents – and in space – to create, build, and invent new solutions in order to address challenges of global importance.

Keep an eye on the challenge website for updates and more details as they become available, or sign up on the site to be updated via email.