Hey Despo, just having a look at the website, attribution non-commercial sharealike looks good.. If you want people to contribute to it and if they liscence their changes they give you credit and cannot pass it on for commercial reasons..
Creative Commons is such a great idea! Browsing their website right now..
Ideally, Codebar (whoever/ehatever that is -- has to be a legal person) should "own" the tutorials and licence them using an appropriate licence (CC-BY-SA-NC or whatever).
Failing that, there should be an agreement with the original author(s) that allows Codebar to operate without any possibility of future problems.
I don't know if this means assigning Copyright or just licenseing things. I'm sure most authors would be happy with any agreement as long as they get credit and know that the material will be used for good (as opposed to evil).
I know a guy who runs a reasonably successful OSS web framework with a lot of contributors. I believe they have a central body that owns the Copyright to the code (and has a policy on keeping it open source etc). I'll ask him how they operate.
@amoe you're right, and there are a few articles online and the CC website itself says a CC liscence isn't the best liscence for source code as there is no distinction between source code and the object and so it can't fall within Free Software or Open Source..