Nielsen, Hitwise, and comScore are all in agreement, so onlookers can perhaps declare it official now: Google had a good December. comScore, the member of the trio that most recently released its search market data, didn't put Google up by a whole lot, though, and unlike the other firms, saw Bing gain ground.
Here are the facts related to that first situation: Between November and December, comScore believes that Google's market share increased from 65.6 percent to 65.7 percent. Which would be fine, or even good, most months.
But both Nielsen and Hitwise thought Google did better in December (both in terms of month-over-month gains and overall market share), so that's perhaps not the most positive news for the search giant.
As for Bing's state of being, comScore stats indicate that the market share of Microsoft's sites increased from 10.3 percent to 10.7 percent on a month-over-month basis. Nielsen and Hitwise had it under 10.0 percent and losing share.
Finally, since Google and Bing went up according to comScore, something had to come down, and comScore placed that burden on Yahoo, along with AOL and Ask. Yahoo's share of the search market slipped from 17.5 percent to 17.3 percent.