I posted something similar to this deep in another thread, but wanted to bring it up again prior to the release.
The question is: what license will the source code be released under?
Given that there is a lot of concern about copycat currencies cropping up after the Nxt release, why not release the Nxt source code with a custom open source license that forbids any derivative work to result in a publicly traded cryptocurrency?
This certainly won't stop others from copying, but what it will do is make major investors and governments far more reluctant about embracing a copycat which violates the license, which will keep the copycat from getting off the ground.
This also won't stop others from using the source code to see how the Nxt features have been implemented and then go and try to do it on their own, but I don't think that is what you are worried about because that will take time, and Nxt will be far ahead.
But of course you need a good lawyer to get the language of the license tight.
I'd love to hear what others think about this.