Still looking for a summer internship? Check out the Google Summer of Code (GSoC).
This is a is a global program funded by Google that pays undergraduate or graduate students a $5000 stipend to write code for open source projects. GSoC has worked with the open source community to identify and fund exciting projects for the upcoming summer. The FAQ is a good place to find out more.
A set of open source projects (aka mentoring organizations) has been selected. Students apply to work on one of more of these and each mentoring organization ranks the students interested in working with them. Google facilitates the final selection and pairing. The mentoring organization works closely with the student to define tasks, check progress, help solve problems, etc. Typically the thudent works remotely, interacting with his or her mentor via email, chat, skype, etc.
Students can submit applications via the Google Summer of Code 2011 site from March 28 to April 8. Google says that that the best applications they receive are from students who took the time to interact with one of the participating mentoring organizations and discuss their ideas before submitting an application. Check out the information on the Advice for GSoC Students Page which links to a list of the 2011 mentoring organizations.