So you are a network administrator and are concerned about Skype (supernodes and all), well take a swing around https://www.cs.uwaterloo.ca/twiki/view/CF/SkypeConfiguration here you will find links to some very interesting Skype disections and tips on how to prevent becomming a supernode.
Be sure to read the text from Blackhat 2006;
https://www.blackhat.com/presentations/bh-europe-06/bh-eu-06-biondi/bh-eu-06-biondi-up.pdf