Here's an interesting complement to both the GSoC model (students work full-time for 12 weeks on a project) and the UCOSP model (students work on a project as one course among N during term): hire a bunch of interns from MIT during their one-month inter-term break, cram them into a room, and give them each one independent task. I expect outcomes will be very good, as it combines collocation (which GSoC doesn't provide) with a chance to focus on just one thing (which UCOSP doesn't offer). It also helps that they're recruiting from a pool of students with relevant experience, and who have already internalized most of the required working practices. Wish we could try this model here, but (a) we don't have an inter-term break, and (b) we don't have money.