Nice work.
one thing I see to make it more streamlined:
elseif ($7 == changed) && ($8 == his/her) && ($9 == nickname) {
change to:
elseif ($7-9 == changed his/her nickname) {
you don't need the split ifs for simple word matches.
8/10
would be 9 with chatspace stylings too.
I really like the word matches for the quits and joins, and hope you don't mind I implimented similar on my own project wallop bar lol.
If you do... tough it's public property now bish! lol