CG Cookie keeps up to date with the latest versions software the crew uses: Blender, Unity, Photoshop to name a few.
New lessons are always created with the newest updates. Our lessons however, are designed to teach fundamental principals that are essential regardless of software version. This tends to give Cg Cookie's content a longer shelf life while teaching a fundamental skill that could be software agnostic.
How old before archiving?
Following our courses using a slightly newer or slightly older version of a program than what is used in the video should not be a problem. If a lesson is deemed to be showing it's age, it will be added to the CG Cookie Archive.
If you do happen to run into an issue where you are unable to follow along for any reason (for instance a feature is moved and you cannot find it), please let us know on the community forum and we will be sure to help you out: http://community.cgcookie.com/