The person replying to that macrumors post was just talking about
viewing contacts within Quicksilver, and not actually resizing
anything in the Mac Address Book. If you have the AddressBook plugin
enabled in Quicksilver, and are using the Bezel interface in the
preferences, you can just start typing a contact name and you'll see
their picture, slightly larger than seen in Address Book. If they have
no photo assigned you'll see a standard card icon. Pressing right
arrow while on a contact in Quicksilver will let you view more info on
that person.
