Ask HN: What makes a great Google Summer of Code application?

This year's GSoC applications are due 04/02. I've been working on mine for the last week (applying for a Ruby gig with Twitter) and I'm at the point where I'm losing sleep, I'm getting so nervous.

To past participants and mentors: what should I do to make my application be completely kick-ass?

The most obvious thing, I would guess, is passion about the topic. I've picked something that I'm passionate about (internationalization, Ruby) and I think that comes across in my application. But what else do I need to know?

Thanks for potentially helping me sleep peacefully again!