Even though no one will admit it, just like in the story of the emperor with no clothes, the age-discrimination bias does exist in the industry; more so in the hi-tech industry. That does not mean that if you are in your 40s or 50s or 60s and are thinking of re-entering the work place you should just give up; it just means that you need to prepare better than someone younger by couple of decades would need to.
I liked this post on this topic by John Tarnoff. Read on if you are trying to kickstart your 2nd act.