Here's an interesting question raised by the latest numbers from the comScore research firm: When Microsoft and Yahoo finally get regulatory approval for their Internet search partnership (assuming they do) which company's search engine will have more U.S. market share?

OK, it's a somewhat facetious question, but the gap between them narrowed to a mere 5.7 percentage points in January, according to new stats released today, as cited by Barron's and others. Microsoft continued to climb, reaching 11.3 percent of the U.S. market. In the meantime, Yahoo kept slipping, hitting 17 percent market share. Google declined a bit, to 65.4 percent of the market.

However, as we detailed last week, these gains aren't coming cheap for Microsoft. Traffic acquisition costs, including search deals with PC makers, are boosting expenses in the company's Online Services Division at a greater rate than revenue has been rising -- resulting in even wider losses in the division.

Analysts are still optimistic: "We believe that Microsoft will continue to build on these gains to form a strong presence in the online advertising market, a potentially needle moving success for the company, with the next catalyst the close of the Yahoo! deal," wrote Sarah Friar of Goldman Sachs in a note to clients this afternoon.