You're right, it's left-over adhesive from the factory paper wheel protectors. If you don't get all the goo off, it collects brake dust and dirt and turns black. Any tar remover, or goo-be-gone, will take care of it.
I've heard that it is clear - but turns black with rubber/brake dust/dirt. The only reason why this point is important, is that if it is indeed rubber from your tires (as suggested above), then it will continually happen. Some how, I doubt that that is true.
It was my understanding per my dealer that is is rubber from your tires, because of the "newness" factor. It was not there when I picker her up, although after a few days of driving, there it was. I removed it, and have been getting less and less, and it is pretty much all gone now/ does not reappear.
Just got my Black on Black S. Black is beautiful, Black is Bitchin', Black is BADASS. I can't believe how stunning this particular car looks in black. The shape of the 997 is very well suited to black. Don't know why but for some reason, to my eye the 997 looks best in black. The problem with this car looking soooo good in black is that it will become popular. Someone else in my garage at work showed up Monday with a black S, Now there are two of them in a garge with only about 70 cars! Fortunalty, he has the standard wheels and I have Champions.
One of my buds told me that the tires I have (Continental Sport Contact 2 - dealer choice, not mine, I had no say) have the tendency to leave that kind of residue on the wheels because the rubber is so soft. I am having such a hard time removing this stuff off the wheel!