Also some menu's and windows as well. In the system preferences, the little search menu will switch to either a blue or grey highlight depending on which selection you choose. In OS X I prefer the blue because just because I don't like the "stop lights" all grey, it looks weird IMO I much prefer them in colour. However I really do like the grey UI and think it would make the iPhone look nicer, but the iPad and iPhone are two different and separate products so I doubt Apple would ever change it. You can always jailbreak the iPhone if it bothers you that much though.