Will Hearts of Iron 3 use Goal-Oriented Action Planning (or a variant thereof)?
GOAP website with in-depth articles.
In a nutshell: Instead of telling the AI word-for-word how it should go about solving a task, it gets an arsenal of actions allowing it to solve the task in different ways, depending on the circumstances.
AFAIK, Empire: Total War uses this concept (not just F.E.A.R. :P) to great success (haven't played it, so I wouldn't know how well it works in strategy games, but the AI blows me away in FEAR2, sometimes quite literally).
Second question: If you didn't know about this (and/or don't want to delay HoI3), will HoI4 (or EU4, or...) use this system? :P