Hm,maybe the only network which use that "forwarding" is Freenode.Atleast this is what i've found HERE.

"This experimental feature is specified with some channel name #foo. When specified on a +i channel (invite-only), users who try to join the channel and are not in the invite-only exemption list (+I) are automatically sent to channel #foo. Clients receive a 470 numeric message which lists the original and the target channels."