Earlier today, Supercell released a small update for Clash of Clans aimed at fixing a few Clan Wars matchmaking issues. According to the developer, the update should help "those clans who havent' been able to find matches." It'll also solve the rare "empty War map" situation.
Clan Wars was implemented earlier this month. Despite some hiccups early on, the feature has been working fairly smooth — at least for me — since. The new feature, as the name suggests, allows clans to wage war with other clans — a feature highly requested by the game's players.