ComScore is changing the methodology for its qSearch market share ratings. Instead of just counting search activity at the major search engines, comScore is expanding the definition of search to include searches at sites such as Wikipedia, eBay, Amazon, MySpace, Mapquest, Craigslist and other vertical players.

Searches across multiple tabs for the same search term will also be counted separately. For example, if you search for “hurrican dean” in Web search and then click the tabs for news and pictures, that will be counted as three searches.

For those who were hoping this might shrink Google’s share of search, think again. Under the new methodology, Google’s share grew 6 points in March compared with the old methodology. The additions to Google (which include YouTube) are greater than all of TimeWarner’s search traffic (which itself benefits greatly from the addition of Mapquest).

Here is a comparison of core search and expanded search metrics based on July 2007 data:

Using the expanded definition, Ask drops from #4 to #7, being passed by TimeWarner, Fox Interactive Media (MySpace) and eBay. TimeWarner moves up from #5 to #4, based largely on Mapquest traffic.

The numbers don’t seem to include Facebook, which according to its blog does more than 600 million searches a month. If that number were comparable to qSearch data, Facebook would be at #5 in the expanded search.

More on: AOL, Google, Yahoo!, Facebook.

Disclosure: I used to work at AOL Search.