My GSoC proposal for Index and Hierarchy API hasn't made it. However, work on those two modules has already started and the first few commits to Index have been made already. At this moment the modules are far from production use. There are a lot of paper scraps and napkins that have sacrificed their lives and now carry lots of sketches and mockups that, in time, will lead to the first stable versions of both modules.
Stay tuned! :)