Yes its true that you can't sell maps of CWBP. The maps are free to use. Nobody can buy the rights to own them and remove the right for you to be able to use them for free. Only Neon as the originator of the top world map can make his map only copyright as well as CC because as an original piece of work which he released as CC, he is able to also release it under any other license he feels like. Everyone else below him is under share alike CC. Now before we all ask him to make an exception at the top level, it would create a problem if he did because if people did that then the project would fork into the same image released as free and the one which was copyright with Neons permission to do other stuff to. It still wouldn't stop the CC side of the fork tho. But you could end up in a situation where part of your CWBP world is copyright WotC or Piazo or something and the rest is not.

Also, on the point of Kaiden, I mentioned this to GP at the time and I believe he took that on board and moved his setting outside of the CWBP and said that if you wanted to set his copyright Kaiden setting in the CWBP campaign world then it would go on the island in the top left but the setting is not a part of or a derivative of the CWBP any more. It should not be marked as such in the wiki or whatever anyway. If it was a derivative then I could take it all and re post it on my own site as CC and there would be nothing he could do about it. Which is not ideal for him really.

You just cant have it both ways where we ensure that the maps in the CWBP stay free and then sell them as well. I'm not interested in contributing loads of time into a project that someone else can buy it out and then sell it on my behalf. I want a guarantee that what I make is, and stays, free for everyone.

Is CC an open source license. Yes. If I take copyright code and release it as Gnu then I am breaking the law. GNU or CC or whatever does not necessarily mean that all the sources used were done so legally. I cant take the latest Spiderman film and legally release a CC mashup of it. What your saying is that all the bits that you created in the map are released as CC. It implies but does not guarantee that all the bit of it that you didn't create as also CC or public domain. If you use elements of the image which were themselves CC with the SA (share alike) moniker then you MUST release your work as CC with SA or else you cant use those sub elements legally. So when we use CC with BY (attribution) NC (non commercial) and SA (share alike) it means that nobody can sell the CWBP and that anyone can take your map and make a derived map from it and that this new map you WILL be able to take and make another derived map from it and so on. From Neons map down and all below it, I can take, use, repost and make derivative works from so long as I also give you that right too. Thats an open source license.

If you take Sony or Spiderman as source then you need permission to use it because it is "All rights reserved". Copying of the stuff being one of those rights. So you cant do it. Since CGTextures is saying that they want to keep copyright of their texture images then you cant use them. CGTextures does state under what circumstances you can use their stuff and its pretty liberal including commercial use. But you cant pass on the rights that CGTextures gives to you when you make your map onto anyone else - including in an open source way. Your not the rights holder and in any position to do so. So really, you cant use copyrighted material in CC works in a similar way as mentioned with Gnu. So they give you the right and you alone not you and everyone else down the chain of open source. In the same way you cannot use CC ND (no derivatives) work in your CC (without ND) works.

That's the beauty of open source licenses is that they don't just give you permission. They give you and the chain of derivatives permission which means that its worth putting effort into something where you need a community to build it because from the things created from your work, you have an automatic right to use as well.

If your interested in open source licenses in general then this is a one stop shop: http://www.opensource.org/licenses