Yes, ageism is real. But there is an advantage to a track record that tends to offset it, depending on the job you're applying for. So stay current and occasionally lay a bet on the industry's direction and you'll be fine. Fact is, a 45-year-old applying for an entry-level programmer position is at a significant disadvantage, not always fairly but that's the way it is.
To be blunt, young managers can be reluctant to hire reports that are significantly older. That's the manager's problem, but if it results in no interview for the older applicant it's his or her problem as well. Only one of the two can do anything about it. That's the way that is, as well.
It's been a wonderful ride but I'm ready for something else. And my own last year has been, in my boss's terms, a "brain suck". I do believe I've written more documentation in that time than in the last I don't know how many. By the time my brain is empty I'll be ready to move on. But I've got 'em fooled - that happened ten years ago. :-)
I am a 36 year old techie. I would be very interested to read more about how you stayed current. I think I am ahead of the curve by moving up the management hierarchy