In the usability and software world ...

Tor: An anonymous Internet communication system. I hadn't heard of it before I came across their user interface contest yesterday. It would have been fun to participate. Here's a snip from their web page explaining the project:

The Tor project, affiliated with the Electronic Frontier Foundation, is running a GUI competition to develop a vision of how Tor can work in a user's everyday anonymous browsing experience. Some of the challenges include how to make alerts and error conditions visible on screen; how to let the user configure Tor to use or avoid certain routes or nodes; how to learn about the current state of a Tor connection, including which servers it uses; and how to find out whether (and which) applications are using Tor safely.

They awarded two winners in February, CMU Usable Privacy and Security Laboratory, and the April3rd team.

If you're interested in software design or usability, you might want to at least scan through the winners. They took very different approaches to the same functional problem.