Dan Crow, director of crawl systems at Google
There is a very interesting article about a talk given by Dan Crow, director of crawl systems at Google, which makes a very handy update about (some of) what really happens at Google.
Here is an extract about getting pages out of the dreaded supplemental pages category:
"Of course, someone just *had* to ask about supplemental results and what causes pages to be banished there. (This is one of the most common questions that I hear at all SEO/SEM conferences.) Dan provided us with some insights as to what the supplemental results were and how you could get your URLs out of them. He explained that basically the supplemental index is where they put pages that have low PageRank (the real kind) or ones that don’t change very often. These pages generally don’t show up in the search results unless there are not enough relevant pages in the main results to show. He had some good news to report: Google is starting to crawl the supplemental index more often, and soon the distinction between the main index and the supplemental index will be blurring. For now, to get your URLs back into the main results, he suggested more incoming links (of course!)."
Whether the information is new to you or not, it is good to have it confirmed from an authoritative source.
The full article is Getting Into Google By Jill Whalen