Cracking Google Summer of Code

As a former GSOC student (and one of the first to land it from my college, that too from a non-CS branch), I can help you with the following -

1. Getting started with open source in general
2. How to build a strong application (I have also been a mentor for Google Code-In and Google Summer of Code, so I have the perspective on what looks like a strong application)
3. Experience with the program and how it helped (I highly recommend Google Summer of Code)