I do think more airlines are signing up for ZED fares. Just a few posts up someone said that UA is starting to use ZED, which is a good thing... maybe they will use ZED with more carriers later.

Alaska (AS) started on ZED last year, with AA as the only interline carrier. Since then, Qantas and KLM have been added (maybe more). Let's hope more carriers sign up with more ZED agreements... they're much better than ID90s.