Now that I think of it, I think David Allen defined the two-minute rule as
applying to things you're definitely intending to do, so, as he formulated
it, it wouldn't apply to someday-maybes. However, the way he described
someday-maybes, they're all big, vague things like "go on a trip to Cuba";
I don't think he would put a 2-minute action there, either. So I still stand
by my first answer although it may not be strictly GTD.