have to disagree here. the reason being that the engine takes longer to warm up when just idling, so the car is spending more time with a cold engine, which isn't good, and it wastes fuel. also it doesn't warm up any of the other oils other than the engine oil.
just start it up, let it idle for 10 seconds or so to make sure all the oil, etc has had a chance to get to where it needs to, then drive off normally and keep it out of boost range. within about 2 or 3km the car should be approaching operating temp so you can start to get into it a bit more, but leave it another min or 2 before really giving it the beans.
as for letting it idle after giving it a hard time, you are best off just doing a lap around the block driving like a granny than just letting sit idling for 30 seconds after pulling up from driving it hard. the reason being is that you will get more airflow through the radiator when driving than just idling, so it will cool down better, as well as the fact that the brakes will cool down a bit. if you just pull up and let it idle the brakes aren't given a chance to cool down so you have a hot rotor sitting in between nice hot pads. with no air flowing around them to cool down.