Google's "Summer of code" project is designed to introduce students to the world of open source software development by giving them payed tasks to do during the summer.
I was one of the ~400 winners of the grant in SoC 2005 and my project was to make a journaling layer for storage devices (under the GEOM susbsytem in the kernel) for the FreeBSD operating system.
Update: I'm also participating in SoC 2006, on gvirstor. More info will be given later...
It's fair to say that Google didn't have the slightest idea what they will be dealing with when they started the Summer of Code project. People applied from all over the world, with different customs and tax regulations, and the organization of the whole thing was terrible. For various reasons (most of which are understandable, but should have been forseen) not a single deadline set by Google for themselves was honoured, which includes various notifications and (important for me) payment. It's not what people expect from a large and internationally visible company.
On the other hand, all agreements were eventually honoured and the staff was friendly enough (if overworked), it was a very interesting project and overall even I will say it's been a success.
More on the gjournal project can be found on the FreeBSD's wiki.