Nothing significant has advertised using it. It's still a pretty new thing, plus it isn't really supported outside of Snow Leopard (although a FreeBSD port is well underway). One thing to understand though, is that it is not some kind of magical "go faster" sauce. If a program does not use every core for everything, it does not mean that its dev are lazy people who need to "Use Grand Central". At the same time, it will not do anything for apps already using all cores, like Handbrake.