I'm sort of torn on this issue. In a lot of ways I really agree with this article. On the other hand, with my experience helping with a first-year college programming course I care, in a way, about the age/level of experience.

I might tailor, not my advice, but my manner of communicating to the age and experience level of the individual.

I really see both sides of this argument but would err on the side of preferring that people not mention their age. This is simply because it does always seem to devolve into an argument on whether or not they should have posted their age.