On the occasion of Yahoo Search's fifth anniversary, ComScore has given Yahoo something to celebrate.

Yahoo gained 0.5 percentage points of U.S. search market share in January 2009, compared to December 2008, according to ComScore, putting the company's share of U.S. searches at 21%.

Microsoft saw its U.S. search market share rise as well. It gained 0.2 percentage points to capture 8.5% of the U.S search market.

Google during the same period lost 0.5 percentage points of U.S. search market share, falling to 63%.

Is that significant enough to indicate that Google's query growth has peaked or that Yahoo is beginning to recapture lost search market share? A spokesperson for ComScore said the company doesn't comment on search data.

All three of the major search engines experienced query growth from December 2008 through January 2009. But Yahoo and Microsoft grew faster (9% and 8%, respectively) than the average query growth rate (7%).

Google, meanwhile, saw only 6% search query growth.

The total number of U.S. queries during this period rose from 12.7 billion to 13.5 billion.

After months of rudderless uncertainty as a potential Microsoft takeover target, Yahoo has a new CEO and has seemingly rediscovered its resolve to compete with Google.

In a blog post recounting the first five years of Yahoo's search engine, Yahoo Search senior VP Tuoc Luong and VP Larry Cornett pledge ongoing efforts to deliver better search technology and to open up the company's infrastructure.

Google may have the upper hand in search, but Yahoo has something to prove. And Microsoft remains in the game, too. It should be an interesting year.

Google, Microsoft, Yahoo, and others are developing next-generation technologies that automate and personalize information search. InformationWeek has published an independent analysis of this topic. Download the report here (registration required).