Hi!
Take a look at

->A Quantitative Analysis of the Gnutella Network Traffic
www.cs.ucr.edu/~csyiazti/courses/ cs204/project/gnuDC.pdf

->Mapping the Gnutella Network- Macroscopic Properties of Large-Scale Peer-to-Peer Systems
www.cs.rice.edu/Conferences/IPTPS02/128.pdf

->GnuMap Project--Creating maps of the full Gnutella Network
http://www.zeropaid.com/news/articles/auto/08192002d

Hope it helps.
Tiago Andrade e Silva