Does Google actually weigh more a link that is older (received in 2001) versus one that is received in 2007. Can they actually check link dates? Or do they consider an older backlink as a website which has your link from that websites creation date..e.g. 1999 versus 2006 Or is just # of quality of links, relevancy, text,.anchor..and link growth being natural as opposed to unnatural. The reason I ask is Zillow, Triulia, CityFeet and other newcomer mega sites in whatever industry have moved to the top pretty quick for certain terms with links from anywhere. When these sites went live they probably got an instant 10k to 50K back links in the 1st month with whomever developed or financed these goliath sites due to relationships with related sites, adjacent businesses, and industry professionals.