The main thing that changed was not the project length, but that the projects are now supposed to be part-time (4 hours per day) instead of full time (8 hours per day).

I'm curious to see how it's going to work out. Halving the student's stippend and the scope of the projects is going to be a big change. On the other hand, it might make it easier for students outside the USA to participate. In other countries the GSOC coding period often overlaps with part of the school year, including final exams.