Dunno, maybe that's the other one but as far as I know CouchSurfing is still alive and kicking (see: http://www.couchsurfing.org - they claim to have almost 3mln users), it's just that it isn't a commercial thing.
Couchsurfing and airbnb offer completely different services. Couchsurfing is free, and very focused on community building. It is definitely alive and kicking.