Well, it's kind of the same as in the Dresden version, really, just much more clearly phrased and easier to understand.
If I create the aspect "disarmed" on my opponent, he will have no weapon, unless he can remove the aspect. While that should always be the case, judging from common sense, the DFRPG seems to imply, that an aspect doesn't do much, if it isn't invoked or compelled.
So it isn't really a rules change, so much as a much needed clarification.