I'm studying for my Dev 401, I've taken all of the video trainings and done all the workbooks. I keep finding all sorts of resources(old dumps, videos, study guides) that are older than 2 years. I'm curious, when it related to Dev 401 are these resources still useful or should I consider them to be out of date and merit no value.
The fundamentals of Salesforce haven't changed per se. If anything, what's happened is that new features have been added. If you look at and older copy of Force.com Fundamentals and compare it to the latest copy (the on-line version is the only one that will be fully up to date, not the downloadable PDF -> Oct '13), you'll see that most of what's different are that it's been updated to reflect new features which have been added to Salesforce since the book was originally written.
So what that says is that if you go back and view various videos available on YouTube and iTunes that were created a couple of years ago and then review the material that covers new releases to the platform which have occurred since that time, you'll be up to date. Most of the new things that are in the above Document are primarily in the last 2 sections of the book with the exception of the Advanced Setup interface for security, etc on objects that was introduced about 2 years ago.