While that's definitely a great way to get icons for sites don't specifically support the iTouch devices it's not exactly an elegant solution. At least for my site, I'd rather users not have to go to that much trouble to see a nice looking icon. Much easier to just put the right file in the right spot once and saves everyone involved a bit of time.
Going by the amount of people who used iPhones at Startup School, this'd be a great little enhancement for a lot of people, myself included.
Agreed that it would be great if everyone supported these icons. That said, boucher's solution is fine for the millions of sites that don't, so I don't know why he was downmodded.
http://allinthehead.com/retro/319/how-to-set-an-apple-touch-...