I suggest that you read the Google Open Source Blog[1]. Information
about GSoC 2010 will be published there. You could also take a look at
the list of accepted organizations for GSoC 2009[2], and see if
anything looks interesting. Getting involved early is always a good
thing :)
[1]: http://google-opensource.blogspot.com/
[2]: http://socghop.appspot.com/program/accepted_orgs/google/gsoc2009
--
Runa Sandvik