Well I googled around and I couldn't find any network called chatnets There was a huge dDoS attack like a few months back on multiple IRC systems is that the one your talking about? If these 'peaple' your talking about are really bots who are flooding channels with the word ATTACK or bots filling the room with names like attackbot1, attacker20, and attack4 then welcome to the annoying and lame world of IRC wars.
Perhaps I could help more if you gave more info 'eh?
Did this 'attack' look like the picture below? If it isn't bots then its probably some kiddies ping flooding or whatever was hosting the IRC might have been DoSed. Humm.... come to think of it you can do lots of stuff on IRC but since I have no info its kinda hard to tell what happend.