DRUPALCON 2012, Open source software and GPL 2
It's useful to remind ourselves, and to whoever works with Open Source Software, the role of GPL 2 llicense, which is the license Drupal uses for all its software. This type of license allows the code to be adapted and shared both as a modification of the original piece of code, or as a new one.
There's a condition though: the code so released must bear an equal or greater degree of openness. GPL 2 can be released as ONLY under the same 2 version or greater.
And this condition is often overlooked in the process of negotiating the openness of an Open Source based website. GPL 2 requires the person modifying and sharing the code to be the legal owner of the code: when developing a Drupal site, for the developer to be able to release the code back to the community, he must not have signed any contract that negates the ownership of custom code.
This condition might seem restricting at first, but if considered under the right light it is an empowering one, both for the developer and for the website owner. In fact the latter is not obliged in any way to share the code: practically this means that he's the owner of the code which is by default his, and cannot be modified by anyone.
Keeping this in mind will be very useful to a developer negotiating a contract with a client who cannot or is not willing to share the code. Actually, depending on how the agreement has been managed, parts of the code can be released under GPL license and others can be kept fully copyrighted, allowing a certain degree of freedom to both parties.
This is the link to the video at the Drupal Conference for the original presentation this article refers to. ( 17' 31'')