As far as I know Clanwars are among the planned code changes, but not actively being worked on at present. (Unless Once has other information)?
Quite a few things have been happening with Clans lately, the new artifacts and ARTISAVE rooms is the latest addition. Together with deeds and possibly clan treasuries, these will provide a target for Clan raids, and the ultimate goal is to open the Clanhalls, (except for the crashproof houses) to raids, but also offer the Clans the option to purchase various defences, like guards, defenders and traps.
I'm not sure if the Clanhalls are supposed to be generally accessible, or just opened to the opponent in an ongoing Clanwar, but hopefully someone else can respond to this.
There is at least one more thread about Clanwars in the Forum:http://4dimensions.org/forum/index.php/topic,660.0.html
There might be others too, but I am too lazy to look for them myself.