Nielsen: Bing Regains December’s Losses In January, Matt McGee, Search Engine Land (Feb 12)
The search market share statistics do fluctuate. In the US according to Nielsen during January it looks like Bing picked up a percent from Google.
Engine / Dec / Jan
Google / 67.3 / 66.3%
Yahoo / 14.4% / 14.5 %
Bing / 9.9 % / 10.9 %
Comscore has figures too - ComScore Releases January Search Numbers (Bing Gains) & Year In Review
Google 65.4 %
Yahoo 17 %
Bing 11.3 %