Mobile searches account for an estimated 10% of Google queries, says Citi analyst Mark Mahaney in a research note released earlier this week. The report, which examined the new comScore search market data, mainly focused on how the use of slideshows by Yahoo and Bing perhaps unfairly boosted their search share ratings.

The mobile search mention itself was nearly overlooked, as it was more of side note in the larger report. Although comScore doesn't include mobile search results in its findings, said Mahaney, those queries now account for "almost 10% of total GOOG queries."

Mobile search queries are "growing very rapidly for GOOG - perhaps triple-digit Y/Y growth," remarked Mahaney in the note released Tuesday morning before attributing the 10% figure to them.

Internet analyst Greg Sterling from research service Internet2Go then further examined what that number means in concrete terms. "Ten percent of 10,292,000,000 monthly queries is 1,292,000,000, or more than 1 billion monthly search queries coming from mobile devices in the U.S. alone," he writes.

In Q1, says Sterling, Google made just over $2 billion from search in the U.S. on Google.com, out of $6.7 billion in total revenue. If you assumed that Google makes the same amount on every search query, 10% of that Q1 U.S. search revenue would be just over $200 million. However, Google doesn't make the same amount on each query, and on mobile, there are fewer ads but higher response rates. The actual revenue, Sterling estimates, would be less than $200 million.

Although these figures are just ballpark calculations, Sterling notes that "it's not crazy to suggest that mobile could be a billion-dollar revenue stream for Google within five years."

Of course, all these calculations are based on the 10% mobile search estimate, so how accurate of a number is that?

Well, last month, another analyst, RBC's Ross Sandler, said mobile search accounted for around 9% of all queries this year - a number close to Mahaney's. Sandler also said mobile search could grow to 20% of all queries by 2012, but a large gap still existed between the number of queries and mobile's share of search advertising. Still, he estimated mobile search advertising could be a $2-3 billion market by 2012.