Well, good news is that now you know what it is.
The bad news is, there is probably nothing you can do to stop the traffic that it is now generating. We have tried many things, but so far the only solution has been to get the domain off our servers.
In any case, you can read more about this at http://www.c0re.net/gnuforum/viewforum.php?f=7
You will find the official "this should stop the hits" solution. And then you will read why certain gnutella clients won't stop no matter what...
Anyhow, I hope this helps.