For years, Google has had Microsoft running scared as it has released product after product that competes for the software giant's bread-and-butter customers. But over the past two weeks, Microsoft has unexpectedly turned the tables on Google with the release of its third-generation search engine, Bing. And for the first time ever, it's Google, not Microsoft, that's worried about the competition.

According to widely published reports from a variety of sources, Google is taking the Bing threat seriously and is racing to add features to its own search engine that emulate Microsoft's efforts. The New York Post claims that Google cofounder Sergey Brin is "so rattled" by Bing that he's personally overseeing the work and has assembled a team of the company's top engineers to develop a response. Hands-on involvement in day-to-day operations by either of Google's cofounders is extremely rare these days, according to the report.

Microsoft's previous efforts in the search engine space have done nothing but hemorrhage usage share to Google and Yahoo!, historically the number-two player in this market. But Bing is different, offering both functional superiority and, for the first time ever, a solution that people actually seem interested in using. Bing briefly overtook Yahoo! Search usage last week, and although that's likely a temporary advantage, it's pretty clear that Bing is a more compelling search solution than earlier Microsoft efforts.

Google hasn't officially admitted to being spooked by Bing per se, but some of the company's public statements are telling. Google CFO Patrick Pichette said last week that the online giant would "review Bing with the executive committee." And a Google spokesperson noted that the company "always has a team working on improving search. We dedicate more time and energy to search than anything else in our company. Our algorithm is constantly evolving."

Presumably, it will evolve to address Bing.