Here’s Compete’s relative ranking of the top search engines for December 2006:
And here’s comScore’s December 2006 US market share data (6.7 billion total searches):
The two sites disagree on Yahoo! and AOL directionally. For Yahoo! comScore shows a gain; Compete shows a loss of share. Regarding AOL, Compete shows a bit of a recovery while comScore shows further erosion.
To throw in a bit of local search perspective: the local products of the majors are capturing about 1% of the traffic of general search. comScore says local search is 13% of all search but it’s a much bigger number when you consider (per WebVisible-Nielsen research) that as much as 51% of local search queries don’t carry a geographic modifier.