With CS, it seems like every company's looking for young, energetic undergrads fresh out of college who know the latest technologies, in many cases to replace the older people. It's always seemed a little too short-sighted to me... not sure how my generation of CS majors is going to do in the long term.
The way to bet is "very badly", and if you're a conventional salaried employee have your exit strategy well in place by the time you hit 35. Expect to be conventionally unemployable at 40, unless you can hide your age.
29. I don't expect "conventional employment", as defined by VC-istan or the corporate megaliths, in 11 years. Those will exist, but I don't think they'll be where the exciting action is.
But yes, if you're applying for subordinate positions that any idiot can fill, and you're 40+, you did something wrong. You don't need to be a manager by 40, but you need to be at a level of skill where it's obvious that you don't need traditional "here's work, go do it" management.