RTEMS Project had 6 students accepted for Google Summer of Code 2009, with one additional student that was funded through the donation that Google gives to mentoring organizations in conjunction with a donation from OAR Corporation. “The first three projects presented were interesting as individual efforts but there was an overlap at the end in what we called "bonus" work. We asked each student to identify pessimistic, realistic, and optimistic deliverables. The work in the optimistic phase was the "bonus" work. Software development is not always easy to predict and the lesson we wanted to impart was that a customer (e.g. us) was more likely to be happy if you told them what you thought would happen if everything went smoothly, if you got bad breaks, and if things go as you expect they will. Our bonus was seeing the cross-pollination that’s common in FOSS,” Google Open Source blog.
More info: 2009 Google Summer of Code