The number 6 search in Google's Zeitgeist this year is Wikipedia and number 10 is wiki. This may mean two things. First, Sunir Shah's clear statement of a popular theory is that Wikipedia Eats Google.
because Wikipedia is the Internet's encyclopedia, many of the articles have included resources from the Google searches on that topic. Over time, Wikipedia has been slowly eating the entire Web's knowledge base until it becomes itself a faster, better, and -- most critically -- unspammed reference matter of what are the relevant and valuable resources. And unlike mere link directories, it doesn't simply list links, it tells a story about them.
The second point, which supports the first, is people are adding these terms to their queries to get better results. People may prefer results not just validated by link count by others, but with edits by others.
This is the flip side of social search, where not only relevance is are improved through social means, but results.
UPDATE: Jimmy Wales launches Wikiasari social search