We hired a mid-40s dev recently and he's great, I think a lot of it is contingent on where the person lives and what the demand is. I'm not in my 40s yet but I've found the older the developer, as long as they have a passion for it, the more measured they are and more willing to put their ego to the side and adapt.

Maybe they won't keep up to the clip a 20s-30s year old will be with learning new tech, but I think there are both pros and cons between a young person and an older person.