[adlwalrus]

I'unno, man. It's probably significantly lower than 99.99% of chrome users that stick with Google as their default search despite the first-run search engine selection dialog, but also likely not too much lower, either.

What's important is that they give the choice -- not just in a tucked away settings pane or whatever, but actually flash the question in the user's face in a meaningful way. If search engine monopolies are important enough to add "friction" to user interaction, then I'd say CA oligopolies are at least doubly so. The conflict of interest factor isn't present in the case of CAs, because, AFAIK google doesn't run any themselves (yet), but I think its still very important to give users the choice.

I also want to point out that Google runs all kinds of infrastructural nodes all up and down the internet's stack. They have no problem pioneering high-performance DNS to move the web forward, and they even are running their own fiber optic network, for crying out loud. They're huge on promoting IPv6 adoption, (mainly because it will remove any significant cap on the internet's (and thus their) growth). I think they can handle a few SSL notaries.

But security behind the scenes doesn't contribute to a palpably sexy image of the web in the masses' minds, so it doesn't really help google's bottom line enough for them to care. Kind of like how while their "speed" initiative complete with JSCDNs is terrible for privacy (third party resources sending referrers to Google upon fetching), it helps to make the web seem like a more serious platform in the subconscious minds of users by increasing performance.

[StavrosK]

Sure, they can handle a few CAs, but then you've switched from the CA oligopoly to a Google monopoly. A significant fraction of the web would basically be running with Google as its sole CA.