Im sure it works the same on a PC, whatever your syncing up with should have a way of making different groups, and you just tell itunes to sync with those groups. As far as im aware you cant do it on the iphone.This is Mac only? I'm not sure how you would do this on a PC, or on the phone itself.
Well i for one wont ever urge you not to get a macMakes sense. While I see the "selected groups" radio item for contacts in iTunes, it does not seem to be an option with MS Outlook, and I don't have the Yahoo application.
Maybe if I get a Mac I'll revisit this.