MirageOS will part of the Google Summer of Code 2014 program, thanks to the Xen Project's participation! It's been a few years since I've mentored for GSoc, but I still have fond memories of some great projects in the past (such as the legendary Quake testing we were forced to do for hours on end). I've already received a number of queries about this year's program from potential students, so here's a few things to note to become a successful applicant.
Students still need to apply and be accepted. Your chances of being selected are much higher if you demonstrate some participation and code contributions (even minor) before submitting an application. Thus, even if you don't have a copy of Xen around, roll up your sleeves and head over to the installation instructions.
Contributions do not have to be just code. They can be documentation, help with packaging, wiki posts about a particular use, or test cases to improve code coverage.
Under some circumstances, we can provide resources such as a login to a Xen machine, or delegated credits on a cloud provider. Don't let that stop you from applying for a project idea. In general though, it's best to only depend on your own computer resources if practical to do so.