Google's upcoming identity crisis

"If they are successful, they will eat into Yahoo's business to some degree," Jupiter Research analyst David Schatsky said.

Analysts conjectured that Google might populate home pages with banner ads, as rivals have done. Mayer didn't rule it out, but said the quality of ads in terms of targeting the right audience is more important than ad type. Figuring out how to do that can take months, she said.

"There's a lot of research to be done here," she said. "But I would be inclined toward text ads."

The issue goes to the heart of Google's identity. Google's enormous popularity has a lot to do with the uncluttered simplicity of its home page — an oasis to many in a world of ever-busier, flashier Web designs. Google's plainness also speaks to the company's early reputation for putting the concerns of users ahead of, or at least on equal footing with, those of advertisers.

That's why some industry observers applaud the company's decision to leave its "classic" home page untouched while introducing the personalisation option.

"If you want more from the service, you can get it — but it's not being shoved in your face, at least for now," Danny Sullivan, editor of Search Engine Watch, wrote in his blog.

But as Google pursues a road closer to Yahoo and MSN, will its do-no-evil mantra ring true?

In the end, it may not matter. After all, the privacy dustup over the way Google places target advertising on Gmail — by scanning the text of private messages — has not set the company back much.

"The best thing that comes out of all of this is that it's going to accelerate innovation, not only from Yahoo," Gartner's Weiner said. "It's going to be a real nudge to Microsoft too, and you can't leave AOL out of the pack. The consumer is going to benefit."

What Google does next is anyone's guess, but analysts have their theories. Weiner thinks Google will introduce an instant-messaging product within six months, either by acquisition or by building one in-house. It's a major feature that Yahoo, MSN and AOL all offer. "Until they have an IM strategy, they're not fully engaged," Weiner said.

Analysts also expect Google to open Gmail up for public consumption soon. Google has kept the free email service in beta-mode, limiting the number of accounts to those who are invited to join. Offering a home page without email is "kind of odd", Search Engine Watch's Sullivan said.

Further out on the horizon, analysts see the Google home page as a platform for introducing more kinds of media, such as audio and video content. TV listings are another possibility, Sullivan said.

"The thing to watch is, Google is good at doing stuff that's different — features no one was expecting," he added. "They won't completely match everything Yahoo offers. They always have to do something no one else is doing."