Spotted on CSN the what I thought first custom CZ mission pack but as it turns out there are already a bunch of them available on the Steampowered.com forums.
The "Black Sun: CS: Condition Zero Mission Pack" has been updated two times already actually and the author states that there will be more updates in the future. Here is a short description of the pack!
You are the leader of an elite terrorist cell, its name not widely known, and have now been called upon to perform Operation Black Sun. The counter-terrorists of the world won't stand a chance against the hellfire you'll unleash.