incredibly useful. This is hands down the most easy way for us (JavaPathfinder) to get interns funded, and students are generally very motivated. For example, from GSoC'10 we got an interactive debugger interface for the model checker ala gdb - serious stuff. The most valuable thing for us is to learn about new talent. We even hired some of them subsequently, which was much better to justify on the basis of successful GSoC projects.

Not to shamelessly use this for advertisement, but this *is* actually our focus this year - hoping that we can get students interested in model checking/verifying Android applications with Java Pathfinder (see http://babelfish.arc.nasa.gov/trac/jpf/wiki/events/soc2011#android/)

see http://science.slashdot.org/story/05/04/27/1510204/NASA-Goes-SourceForge
And this was not just a toss-over-the-fence. Most of the projects on http://babelfish.arc.nasa.gov/trac/jpf are actually maintained by external collaborators, and JPF just applied for its 3rd Google Summer of Code participation. With all the domestic and international research collaborations this has been a good success story for NASA.