Microsoft’s Keyser Söze Opportunity

The thing is that the bulk of the market is remarkably non-tech-savvy. If Bing became the default search engine on Firefox it wouldn't alter my searching habits at all, as I'd just set it to Google instead.

However for the nontechnical majority, if it still returned the results they wanted there's a good chance they'd never get around to solving the hard problem of switching default search engines.

Indeed. It's telling that even though the default search option (through the search bar and the default homepage) for every IE browser is an MS search site the marketshare for MS search is so low that at most 25% of IE users use it. Maybe that's because a lot of people who use IE don't search as much as people who use other browsers, but ultimately that's irrelevant.

Every indication is that people who use search prefer Google (and to a lesser extent Yahoo) over MS search by an overwhelming margin, regardless of the defaults. Switching to a less popular default search site for iPhone users is a certain recipe for user annoyance and customer dissatisfaction, and hardly some grand sweeping strategy that could pull Bing's popularity out of the doldrums.