I'm 64 and started as a mini computer tester in the mid 70s. Within two years I was forming my own programming team at one of the early microcomputer companies. I've been programming ever since.
I'm proud of the skills I've acquired over the years and the projects I've worked on. And I never think my skills are enough, lately I've worked with meteor, zero-copy packet architectures, iPhone apps, and some security-related issues.
I'm not going to try to hide my age and I'm not going to try to make it a desirable trait. I will hope that bit of ambiguity gets me in for a face-to-face interview which I am very confident will turn out well.
Companies which are so rigid as to wonder whether I'm "young enough" are probably not places I'd like to work anyway.
Actually, due to the fact that my kids are grown up and out on their own, I am not nearly as concerned about getting top dollar (or climbing some career track) as I am about working on something interesting and having done something I can look back on 10 years from now and feel that my time was well spent.
Over the past couple of decades I have become more inclined to stay in a position due to the fact that I am not feeling the need to make more money or climb the corporate ladder. I wouldn't take a job that was going to be boring but I also know that a job is often what you make of it. My experience has always been that there's always challenging work that others don't want to take up because it's not on their career path, not high profile, and etc.
I appreciate the value of what you have said but I wonder whether the deception by omission would count against me in the case that I get as far as the face-to-face interviews.
Thanks!
ps. The 40 years includes only the years I was paid. Prior to that I spent about a year learning how to program.