I don't frequent Google blogs, but I visited today and found a post most of our members will find very useful, excerpt below, link to the full post can also be found below:
Search Quality is the name of the team responsible for the ranking of Google search results. Our job is clear: A few hundreds of millions of times a day people will ask Google questions, and within a fraction of a second Google needs to decide which among the billions of pages on the web to show them -- and in what order. Lately, we have been doing other things as well. But more on that later.
Full Google search quality post
Search Quality is the name of the team responsible for the ranking of Google search results. Our job is clear: A few hundreds of millions of times a day people will ask Google questions, and within a fraction of a second Google needs to decide which among the billions of pages on the web to show them -- and in what order. Lately, we have been doing other things as well. But more on that later.
Full Google search quality post