The libapt-front effort is to have a better API for APT than the current libapt-pkg provides. It should provide easy, but powerful and flexible API, one that would suit programmers of both CLI and GUI programs based on APT. Also, the API, if at all possible, should be exported to some scripting languages, like ruby and python (others covered by swig come to consideration, too).
There is an architecture overview of the libept library. There is a scarce comment here and there in sources, but beware those out of date… Fixing up the documentation (at least cleaning up the misleading parts and providing some example code + the overview) is a part of the plan for libept 0.4.
Mornfall’s current development branch is stored in darcs: repository.