Google is now introducing their "Google Summer of Code Program". It's a highly competitive open source coding camp where students are paired with a mentor, presumably a current Google coder or other similar employee, and then contribute to ongoing projects.
See accepted projects here: http://www.google-melange.com/gsoc/program/accepted_orgs/google/gsoc2012
Google will be holding a hangout on Google + for a Q and A with one of their current coders. Info on that here: https://plus.google.com/u/0/101571483150813305324/posts
Apply soon, though in may already be too late, because this program, like we mentioned above, is fiercely competitive.