At SEO By the Sea, Bill Slawski has a post on a patent filing by Microsoft in using the age of a domain to reduce the impact of link farming on search engine results. The concept uses the information obtained from the domain hosting a site to calculate the age of the website.

An excerpt from the article

This patent application assumes that newer domains have a "higher likelihood of being spam and/or being a part of a web farm that attempts to artificially inflate domain rankings for domains in the web farm."

By looking at the age of domains that link to those newer domains when determining a rank for a domain, domains which have links from older domains "may be ranked higher than spam domains and/or less relevant domains."

The concept is novel in that it does not affect the rank of the source page as such but affects the rank of a page linking to the source page and looking to benefit form the link 'juice'.

The technique does seem to theoretically be very effective in curbing link farming but that means to have a relevant site you have to now onwards be really consistent and regular. Posting regularly over a long period of time must now make a difference in the rankings for a site.