Google sent two Nexus S phones as part of the STS-135 mission with a goal to use Nexus S on the International Space Station to explore how robots can help humans experiment and live in space more efficiently.
In a blog post Google Mobile Software Engineer revealed that "NASA is using Nexus S phones to upgrade a trio of volleyball-sized SPHERES (Synchronized Position Hold, Engage, Reorient, Experimental Satellites), originally developed by MIT." "The phones help the robotic satellites perform tasks the astronauts used to do, like recording sensor data and capturing video footage."
Google Mobile engineers said that a "couple of our engineers built an open source sensor logging app that NASA decided was perfect for running diagnostics with the SPHERES."
You can download the same app yourself from Android Market.
You can learn more about the project on NASA's website.