I believe a network should be able to sell priotitization at the edge,
but not in the core. I have no problem with Y!, for example, paying a
network to be prioritized ahead of bit torrent on the segment to the end
Considering yahoo (as any other big freemailer) is (unwillingly for the
most part) facilitating a lot of spam traffic this would mean a lot of
spam traffic gets prioritised. I can see that as an undesirable and
unfortunate side effect.