So I thought about this a bit and while I'm for it, I can see a potential problem: if/when PW becomes a much larger community and there are hundreds of alliances and I can see this falling apart to a certain extent(or we end up making the qualifications higher). Assuming this is put into place, I really don't think it should be like a weekly/monthly thing. For one part it may be a bit tedious, and the simple truth is just not every alliance in game will get along; while I do think that this would be nice maybe bi-annually/annually/every three month -- and of course emergency ones may be called I suppose.
The radio thing is a good idea though and I can only see that doing good.