I don't think anyone will give you a clear answer on this one because no one knows what google is really thinking but I don't think age has much to do with content to be honest. If the content is well spread out over the internet and with several backlinks it will be stronger in the search engine results. Also most information that is aged tends to be bad information because it is outdated and new things have come out. Content age is irrelevant I would say.

Have heard of it many years ago. It's related to the cached page in G. But I don't think it's what G want to seriously consider this unless the content comes from an authority site...

No I really don't think so as far as what I have read SEO experts says that the content needs to be updated...So no question of aged content..Spiders love fresh content....

aged content? Geez, it ain't fine wine! Seriously though, as some have already alluded, more than likely, in time, Google gets a better idea of where your content ranks, relative to other content like yours. And that's really it. Because for every "aged" content that Joel Comm points out that is performing great, I can point to so many more that have fallen off SERP nirvana, or gasp, even managed to get themselves de-indexed. Of course, I can't point to a de-indexed page, but you get the idea...

Domains age.

Your domain should perform better if you have relevant content on an older domain.

Content doesn't age, but the link hierarchy coming to your content will get stronger over time. (giving it the illusion of old content performs better)

I stumbled upon an Ezine article written by me few months ago, which currently has a PR5. I have never linked to this article personally.

Domain age is also a similar thing. If you have a domain parked for 3 years without any indexed content, it has the same value of a domain registered yesterday.

I had a post in my site that used to be on page 12 of Google, and now it is sitting on page 1 with no backlinks, and the content is not even link-worthy.

It is most likely due to domain aging, homepage's linkjuice is passing down to that page to give it a bump in the SERP, or both!