Yesterday Microsoft’s Bing announced a partnership with Twitter and Facebook to make its “decision engine” more social. And not a day later, Google’s Marissa Mayer was up at Web 2.0 announcing that Google would be launching similar services soon.

It appears Google is a little worried about Bing. And that’s great news for Twitter.

Bing’s new features are available now at Bing.com/twitter, while Google’s social launch is still a few months off. Until Google launches, a true comparison won’t be possible, but the first differences are that tweets will be integrated directly into Google search results (as will info from users’ social graph), while Bing will search all tweets on a separate page.

For now, users are sticking with Google. The company increased its market share in September to 80% from 77.6% according to StatCounter, while Bing’s popularity fell nearly 1% to 8.6%. But Google’s quick rollout directly after Microsoft’s announcement proves that the company is keenly aware of the moves Bing has been making in the space.

And while Google has a tight grasp on the search market with over 3/4 market share compared to single digits for Bing, the search giant is well aware that it’s earned its dominance by incrementally improving search until it could blow the competition out of the water.

If Bing can do that now, Google could be in trouble down the line. But as Google proved this week, the search giant is happy to replicate any cool new features Bing creates to protect its position.

So who’s got the most to gain from this copy cat approach to search? For now, it’s Twitter.

Some reports speculate that Twitter received “millions of dollars” from both companies and/or a revenue share on both search engines. For a company that is expected to earn $4 million this year, any revenue share with the major search engines would be a big deal.

A source tells Silicon Alley Insider that Twitter CEO Ev Williams
recently said he
wouldn’t give Google access to Twitter’s data for anything
less than a $100 million guarantee. While it’s looking like Twitter
didn’t get nearly as much to share info with Google, there’s a lot of
room for windfall for Twitter. From SAI:

“Our source, who doesn’t know what Google paid –  but is familiar with
Twitter’s plans — guesses Google agreed to a revenue share on pages in
which tweets show up, with a nine-figure guarantee to be paid out over
a two to three year period.”

Twitter’s founders have been talking a lot about finding their revenue stream through all of the marketing that’s happening on Twitter, but this is a great place for the company to start monetizing.

Regardless of how much money Twitter gets upfront or on the backend of these deals, integrating itself into search is a great move. A continuing issue for Twitter is that microblogging is not entirely proprietary, and it truly depends on the whims of social users. The company could have tried to go it alone with a real-time search engine instead of working with the big guys, but that would simply give consumers — and other search engines — more time to get acclimated to a different microblogging service. By partnering with Microsoft and Google in brand agnositc partnerships, Twitter manages to further cement its hold on real-time search.

What does this all mean? That when Microsoft and Google compete on search, smaller companies (with proprietary technology) win

Image: Bottlecap Development