[gribbly]

>In my experience money is a key incentive for students in GSoC and that makes it hard to keep them as volunteers.

I think that's a bit pessimistic, bottom line is that during the summer, a lot of students take on jobs to improve their finances (at least back in my days), back when I was a student I would have loved being able to work on projects I love/interested in and getting paid for it, rather than, as in my case, pretty much waste my summer time working in computer/video game retail to earn some bucks.

So yes, money is an incentive, but you could probably make that money in a regular summer job, the big boon as I see it is to work on something you find interesting during the summer, which in turn increases the chance that you will want to continue working on it once GSOC is over.