You should be happy, you must live in a area where everyone uses Gnutella, all IPs of your ISP have been using Gnutella lately.
Or it's more like your "dynamic" IP isn't - you should write it down and see if it really changes.
Ignore the hits, change zonealarm's settings to ignore it, or get a real firewall that doesn't pester you to get you to BUY the "pro" version.
Why do you think it pesters you so much? People have been complaining about this program for months now.