I had friends of MSN Messenger, Yahoo Messenger, GTalk and for a very limited time ICQ (Actually it was the same guys on all networks :) ). There weren't any network effort, people were willing to try out different IMs for their uniqueness.
Lots of companies were trying to produce integrated chat clients - Pidgin, Meebo, Trillian, Digsby and a whole lot of guys on Mobile targeting Symbian OS (could recollect only Nimbuzz though.) I loved Digsby because it acted as a POP client too.
I even worked for a company that forked Ignite Realtime Spark and tried adding Gtalk and MSN support. When I was freelancing one guy asked me to clone meebo for $500 .. and I accepted :facepalm.