What kind of mentoring organizations should apply?
As you can see from the lists of our mentoring organizations for 2005, 2006 and 2007, many different types of open source projects participate in Google Summer of Code. As long as your project can provide mentors and is releasing code under an Open Source Initiative approved license, you are welcome and encouraged to apply. Unfortunately, there are far more great open source projects than we can work with, so if your project is highly niche or has very few users, chances are that your application will not be accepted. You may also find our Notes on Organization Selection Criteria helpful.
