They say that the best defense is a good offense. Google has built their battle plan around this concept. The theory goes something like this. If Microsoft can use its power to hurt us via its Internet Explorer browser or in other ways, then our Obi Wan Kenobi (for non-nerds: only hope) is to diminish the power of Microsoft and Internet Explorer to the point where it is not strong enough to hurt us.
One of Google's strategies has been to defend its search engine business by increasing the number of reasons a user would come to the Google web site regardless of any browser settings. Other businesses have used this strategy for a long time. Chucky-e-Cheese Pizza does not try to have the best pizza around. Instead, they get you to come for the video games and shows. Once you are there, you'll buy the pizza, and you'll keep coming back. Google has various applications do achieve a similar result. Google Maps, for example, doesn't make much money for Google, but it ensures that people looking for maps and directions will come running to Google.com regardless of where their default search box points. And, while they're there, they just might click on one of those ad links, and ka-ching!
Other ventures like the image viewer Picasa provide the same kind of loyalty. A user with hundreds of photographs carefully cataloged and shared across their Google provided accounts isn't likely to stop using Picasa just because someone directed them somehow from the more traditional Google search. In fact, Picasa offers a program that is directly installed on the user's personal computer. If there ever came a time when Microsoft figured out some sort of nuclear option to shuttle their users away from Google, Google could retaliate by upgrading Picasa and including a counter-strike, like a default install that redirects users back to Google. This strategy is already used somewhat ham handedly by Apple in their iTunes product. Upgrades to iTunes include the QuickTime video player no matter how many times you uninstall it. The latest even come with a new web browser (Safari) that installs just by the user clicking the button that they think does nothing more than make their beloved iTunes better.
The Google Calendar, and Google Reader, are other resources in this vein. They all give users reasons completely unrelated to traditional search functionality to repeatedly visit Google either directly, or through the interface of the product. The acquisition of Youtube added to this list by also ensuring that millions of visitors will visit a Google property while looking for videos. This move allows Google a way to tap into less savvy computer users, the kind who are not likely to subscribe to RSS fees, or use any calendar other than the one their employer threw on their computer.
Perhaps the most successful blow on this front has been Google's Gmail service, which grew quickly by offering simple but complete email functionality for free, with much more storage than competing email systems. This maneuver caught Microsoft flatfooted at the time. Microsoft was targeting Yahoo Mail back then and worked to match those features, not Google's. When they looked up, millions of users had Gmail accounts precisely because they did not have to pay for email forwarding, or extra storage space. Now, Google's installed email base can be counted on to go looking for Google no matter what Microsoft does with its browser. After all, all of those users will still need their email regardless of any Internet Explorer or other upgrades. And, while they are there, Google can always provide a nice easy button to reset that pesky search box back to Google. If that doesn't work, Google can always suddenly come out with a directly installed email client to "meet customer demand."