An article in Sunday's New York Times, Google Keeps Tweaking Its Search Engine, goes in-depth with Google's Amit Singhal, one of the Google engineers on the search quality team primarily responsible for building, maintaining and tweaking its ranking algorithm.
Saul Hansell from the Times spent a day with Singhal, Udi Manber, Matt Cutts and the search quality team, and his story offers some insights into Google's inner workings, including some that previously had been hypothesized by SEOs, but never confirmed. Rand Fishkin does a thorough breakdown of the article at SEOmoz.
Among the topics discussed are how Google handles bug reports, and its own concerns with freshness of its results, including details on the development of the "Query Deserves Freshness (QDF)" solution that determines which queries should show results from new pages, and which should rely on established sites. The article also goes into detail about the 200+ "signals" that are fed into "classifiers" to calculate a page's relevance.
Matt Cutts has posted about the article on his blog, in Five things you didn't know about Google's search.
What clues into Google's algorithm did you find most useful? Share your thoughts in the SEW Forums.