Here's a shocker: Google is the dominant search engine, with 63% of all U.S. Internet searches in August 2008, and that's up 6.5 percentage points from a year earlier. Google only has 58.6% percent of the worldwide search business however.
These facts come courtesy of Ad Age and its incredibly informative Search Marketing Fact Pack 2008. It's available free in online form and in print for Ad Age subscribers. While I'm sure you didn't need a "fact pack" to know that Google is crushing its competition, there are 30 pages of other search-related marketing data that I'm sure you will find interesting.
Speaking of search marketing, I'll be doing a webinar on "optimizing your content for search" on November 24 with Mike Moran, co-author of Search Engine Marketing Inc., a great book on the subject.