You know I was thinking about this a little overnight. I still think it's at best very, very unlikely to ever see WoW on an iPhone. However, what about this? A widget/iPhone app that allows you to log onto a character and not actually play the game, but to have access to the following:
1. Chat channels
2. Mail
3. Bank
4. Auction House
5. A generic vendor/repairer
6. Various panes such as trade skills, character screen, rep, etc.
Restricting the app to these things would mean you'd need a limited amount of graphics and graphics processing power (basically item icons and some 2D interface UI). I guess you'd have to have your character parked in a capital city to access certain things, and maybe this special app would allow you access to bank, AH, and Mail without having to physically move between them. I'd love to be able to do Arcanite Bar transmutes from the airport, chat with my guildies, and check my auctions when I got off the plane

As weird as this sounds, an app that gave me these things might actually get me to buy into an iPhone.