There are 2 lines of thought on this from what I have read on T'internet. One is warm the car up, and drive it hard for a good while up to the red line, apparently the piston rings will seal better if driven hard as they only have a short period of time before they harden. After 100 miles of this then drive it normally to let everything "bed in"
The other is treat it gently and not rev it to the redline, vary the rev's and not let the engine "labour". It mentions this way in the handbook. I have spoken to some mechanics on this and they have different opinions. I suppose it depends on if you want your car for a short time then trade it in, or want it to last a long time and look after it.
If treated hard from new the engine seals better and has less friction, meaning it loosens up faster and produces more power, I was told.
I personally chose the tender aproach to my GTI after hammering my S4 from new, including 2 laps of the Nurburgring with under 1000 miles on the clock