Even if the full instructions covering a whole GSoC / FOSS OPW internship can be really complex, THE POINT is very simple, and many times it gets lost with all the details.
Proposal: design a single wiki page with the minimum text (initial draft provided by @Qgil) and some graphics (that you could borrow from Commons or The Noun Project).
This is a candidate for a Google Code-in task, part of T561: Prepare Wikimedia's participation in Google Code-In
Draft text coming soon (below):
Find inspiration for a good wrap-up post: http://moriel.smarterthanthat.com/tips/google-summer-of-code-2013-summary/