Guys from Promodo SEO company (they listed within top 10 by "SEO services") just published perfect (IMHO of course) article about Google time filters (Google Sandbox) with Generalized scheme of Sandbox algorithm work. The url is http://www.promodo.com/articles/search-engines/2.html
my goodness, I cant read more than 2 paragraphs of that article...its as if they took the original article and put it through a content rewriter. Sentences seem backwards, and many words look like they were substituted for synonyms.
I'm an author of that article. The original article is on Russian (http://www.promodo.ru/articles/foreign/163.html). Maybe, our translator did this work not so qualitatively as we need. I'll solve this problem. Sorry for inconvenience.
It is a good article on how Sandbox algorithm work and the Google filter. You are right Google is a powerful search engine and system today that is mostly used by the SEO as to achieved a better result for the site. The result for Google is not just easy but a lot of hardwork and patience.
What is clear is that google has filters in place that affect rankings. Whether this is done by discounting links based on age or by the actual age of the site is all speculation. I felt that article was making mountains out of molehills.
I think that anyway some of the filters we could evaluate based on common sense An old link can't be "cheaper" than the new one.