This months issue of "My Ford" magazine explicitly asked this question of whether you need to let your car warm up before you drive it and the answer is no. This is my 2cents, but if anything, prolonging the period where your car idles with cold fluids is going to be more detrimental than getting the car moving and the engine revving some. The sooner the internals reach normal operating temp, the better. With modern cars it probably doesn't matter either way, but except for getting the interior comfortable and defrosting windows there seems to be no reason to let your car sit and idle. I think it comes down to a matter of preference, but you won't be harming your car by getting in and driving it right away.
Why would our cars idle high on cold start up if not to get the internals moving and fluids warming up faster?