David Kirkpatrick of Fortune published an editorial on the stumbling dance between Google, Yahoo, and Microsoft. He's mostly right on the old-school business issues, but he misses a lot on tech and what it means.
They seem to have gotten the idea that Microsoft's search has caught up with Google's technologically, but they provide no justification for that opinion. (On an anecdotal note, shortly after the previous entry was crawled by the msnbot, I started getting links from them on "traffic" from the UK.) It seems like he's just repeating talking points or fishing for advertising dollars.
Google is still unequivocally the best search engine to use, but Kirkpatrick is right in that this doesn't really matter much for Google's bottom line (but wrong on why). Google makes it's money by buying and selling advertising. If it owns the destinations those ads are ultimately served on, great, they get a bigger slice of the pie, but they're just as happy to split it with anyone else.
That's where Google and Microsoft part ways. Google isn't threatened by Yahoo existing alongside them offering search and mail, in fact they're quite happy to sell ads for them. Microsoft cannot stand the idea of anyone, anywhere competing with them. For them, it's all or nothing. Microsoft needs to get it's hands on all the pie, where as Google will just make more pie.
Where does Yahoo fall in this? They're just fine where they are. They're in the red, and Google isn't going to crush them for daring to compete. Microsoft would certainly like to, but they haven't the ability. Yahoo's visitors are almost all going to be people using Microsoft's operating system and browser which will default to their search engine and other things. People visiting yahoo.com have made a conscious decision not to use Microsoft's web services, and that's not going to change if Microsoft buys them.
Google can get away with buying web services because people like them (and they don't change them for the worse). People don't like Microsoft, so expect an exodus of visitors from Yahoo if they get their mits on them. Most of those will go to Google, and there will be a bloom of independent implementations of things Yahoo does well, like Flickr. Don't be surprised if Google is one of them.
Kirkpatrick thinks Google has an Ebay like hold on the ad market, but they really don't. There are lots of other similar services. Google gets the most attention because they've got a lot of goodwill, but they could easily be overtaken in this market if they pissed people off. Unfortunately for Microsoft, that's not particularly likely to happen, and they've got such a terrible reputation that they'll never be able to match Google's goodwill. Neither can traditional advertising companies, who haven't built us lots of cool toys as Google has, and who seem incapable of knowing when to say 'no' to ad buyers.
So no, Google's advantage isn't control over any market, and while they've got some cool tech, that serves mainly to increase the size of their market for everyone. Ultimately, Google's real advantage is that people don't think they're bastards.