Firstly I will say it's not a problem, but rather a DFI characteristic with ALL DFI engine manufactures. I doubt you will hear anything from Porsche regarding this, however they may include a maintenance cleaning scheduled memo with the service centers.
There don't seem to be any issues so far here. The best longish term report so far has been from the Cayman Interseries guys who have reported the new engine is performing flawlessly. We'll know more as the '09's out there start racking up miles but I'm going to go out on a limb (since I'm an '09 owner) that the new motor is very good.