Add to this:
4. All students should submit a miniature, self-done aptitude test as part of their proposal. The Boost build / test / doc chain can be a big motivation-killer for students who just want to get on with coding. Getting that step done before the SoC starts would help mentors decide on the best candidates and give the students a bit of a head start.
+1 There are a number of other GSoC projects that mandate aptitude tests as part of the application project. Beyond getting the toolchain up and running, are there any kind of projects that we should have potential students focus on? Maybe require some programming involving basic STL concepts (e.g., Containers, Algorithms, and Iterators).
5. Encourage toolkit-like additions to existing libraries, rather than writing a full-blown library. These have historically been more successful.
+1 Also a good set of projects. Andrew