Since Prestashop 1.4 has now gone into production, the original Smarty debug module has been updated to support the latest features. Specifically this means that you should be able to debug both Smarty v2 and Smarty v3 Pretashop themes using the tool. You can read more about it and download the module from the Debugging Prestashop Templates page.
Another development module to be released soon is an implementation of a code profiler for use in optimising Prestashop custom builds as well as a new release from our Plugins for Prestashop project. The latter has us fairly excited as it has opened up some really original ways of building stores without the need to resort to major code modifications and overrides.