We all know that the age of a domain affects search ranking. Because of this many websites have resorted in buying old domain names in order to benefit from the aging. This is not a bad thing at all especially if the domain bought is relevant to the site’s theme and the new site being built contains quality content. However spammers are always there to exploit every loophole they could find thus using even this technique and then use the old domain for nothing more than a link farm. Spammers usually resort to link farms because even though aged domains are good lots of links carry more weight in getting a higher ranking. Obviously search engines hate this tactic and have been trying and are still trying to find ways to combat these link farms both “old” and new.
Microsoft has been trying to combat this problem by looking not only at the age of the domain and the number of sites linking to it but also the age of the domain of those sites.* What this means is that although link farms may get lots of inbound links those links wouldn’t hold as much weight as links from older and more reputable sites since most of the sites that join link farms are new ones.
On the other hand, what this means for ordinary sites is that it will make it a bit harder to do link building since we need to get more links from older sites. Add to the that the relevance of the site and all those factors what it simply means is that organic link building is making more and more sense since search engines are finding better ways to determine which sites are really offering something of worth and not.
For a more in depth discussion on how Microsoft ranks a site depending on the maturity of a domain you can read Bill Slawski’s post “Do Domain Ages Affect Search Ranking?“.