There's a "channel" to broadcast to all of the current haven instance you're in, and a channel that goes through all instances for Trading, buying/selling.
Could there be a channel for Coliseum? I'd imagine there would be enough to go on in this channel and there's many things that could be asked and joined through this over a topic, similar to plainly buying and selling items over the Trade channel.
Although it would be a little bit more broad than the trading channel I'd still think avid Lockdown and Blast Network players would resort to this while attempting to wait for players to join their game in the right servers.
(If ever) Guilds could attempt their daring thirst for some steamy Guild vs Guild matches, or other smaller player's wishes and fights to go through in the Coliseum.
This might be a little too broad for such a thing and I guess it just depends on views on how these "channels" are supposed to work and how the trade channel, and the Coliseum are viewed, which I would not be able to say what other players and GMs would think of an addition such as this.
Its not a bad idea!A channel for pvp will help,although if they dont try to promote somehow the pvp on the game i dont think much will change.The people who play on coliseum are the same pretty much.Anyways Coliseum chat channel is a good idea!+1 from me.