ISA sourcebook - is it planned?

Is there a sourcebook planned for the ISA? I ask because my group was talking after a session the other day about cabinet level positions and such and was wondering if a book was going to cover it or if it wasn't something planned.
Oooooooooh yeah, that is a good idea. Would be something to work on after all the base stuff (season books, race books, whatever else is planned) is done.
I agree, I wouldn't look for it until we had a good solid core group of books out on all the races and such, I was just wondering if there was a plan for it :)