My reinvention of the Krang add-on system is well under way. The previous system was little more than convenient way to package source code that could be copied into Krang. It had upgrades and dependencies, but that was it.
The new system will allow Krang to mature into a true application development platform. Addons will be installed into their own space under addons/. This has two important advantages: 1) it will keep addons from accidently or purposefully overwriting Krang source files (and vice-versa) and 2) addons can be developed in-place under version control.
Fixing these two issues should make developing add-ons a lot more pleasant. But the new design doesn't stop there - it also brings Krangs build system to addons so they can come with their own dependencies. A new class factory system will allow add-ons to selectively extend core Krang classes without needing to alter Krang's code. Finally, Krang's left-nav area will be modularized so add-ons can register new entries without having to completely override the navigation templates.
The new system should land in Krang v1.103 sometime later this week. I'm off on a branch for now so v1.102 can get out the door without more QA.
-sam