Basically, what Google says it will do is start displaying fewer ads for queries that are more non-commercial in nature, and more ads (up to its maximum of 11) for queries that are commercial in nature. A product manager for Google's ongoing ads quality initiatives explained the rationale: "We believe that ads provide valuable information when they are highly relevant to what users wish to find -- and that by showing high quality relevant ads, users will consider ads as a first choice when they're searching for products and services. At the end of the day, our users benefit from relevant ads and our advertisers get more qualified leads over time."
So how will Google accomplish this change to the number of ads displayed? It has to do with keyword matching options -- specifically "broad match" and "phrase match." As you know, if you apply broad match to your keyword matching options for when your ads will be displayed, your ads will come up whenever a user's query contains your keywords, "in any order, and possibly along with other terms...including plurals and relevant variations," according to Google's AdWords help page. Broad match is the default option. Phrase match is only slightly more limiting; it will show your ads when a user puts in the exact phrase, in the order you specify, though it will still come up if there are other words in the query. So if your phrase is "tennis shoes," Google would display your ad on a search for "red tennis shoes" but not "shoes for tennis."
I'm mentioning these points because Google will be more conservative about these keyword matching options when it comes to displaying ads for education-related queries. To quote Google's product manager, "If you notice a decline in impressions or clicks on some of your keywords, you may wish to ensure that your most important terms are each specifically entered as keywords in their own right, rather than relying on broad or phrase match to include them. Or, if you notice an unwanted increase in impressions or clicks for some keywords, consider adding negative keywords to more finely tune your targeting."
I know that for some queries it's obvious whether it's mainly commercial or educational. But for others it's not so clear, which leads me to wonder how Google plans to tell the difference on the fly. I remember a while back when the search engines were just starting to make searching more personalized, at least one of them -- Yahoo, I think it was -- came out with a sliding toolbar that you could adjust based on whether you wanted to see more commerce-related results or more educational-related results. I could see using the results from something like that; if you knew most people who put in particular keywords set the slider more towards information- or commerce-related results, you could start making predictions about other user queries. Google could still do it, obviously; the processing power it is bringing to bear behind this must be nothing short of incredible though.
Search Engine News 
