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! :)
Today I published my GSoC proposal: I want to bring Vocabulary Index to the next level. This includes integration with Views and Transliteration. Also, there will be new ways to display data and the possibility to use different template files for different indexes. In short: this baby could replace the Ubercart catalog, Drupal's Forum module and more!
If you want to see this happening, please review my proposal. Thanks!