We have an exciting list of project ideas for QEMU, libvirt, and the KVM kernel module. Students should choose a project idea and contact the mentor to discuss the requirements. The easiest way to get in touch is via the #qemu-gsoc IRC channel on irc.oftc.net.
Student applications formally open on April 22 but it's best to get in touch with the mentor now. See the timeline for details.
I've shared my advice on applying to Summer of Code on this blog. Check it out if you're looking for a guide to a successful application from someone who has been both a student and a mentor.