Some social networks or search systems may take site age, page age, user account age, and related historical data into account when determining how much to trust that person, website, or document. Some specialty search engines, like blog search engines, may also boost the relevancy of new documents.
Fresh content which is also cited on many other channels (like related blogs) will temporarily rank better than you might expect because many of the other channels which cite the content will cite it off their home page or a well trusted high PageRank page. After those sites publish more content and the reference page falls into their archives those links are typically from pages which do not have as much link authority as their home pages.
Some search engines may also try to classify sites to understand what type of sites they are, as in news sites or reference sites that do not need updated that often. They may also look at individual pages and try to classify them based on how frequently they change.
- Google Patent 20050071741: Information retrieval based on historical data – mentions that document age, link age, link bursts, and link churn may be used to help score the relevancy of a document.