The moment Nokia realised MeeGo wouldn't meet their requirements
An article in Business Week, pointed to by Engadget, documents the moment that Stephen Elop, CEO of Nokia decided that MeeGo could not provide the future platform for Nokia: At its current pace, Nokia was on track to introduce only three MeeGo-driven models before 2014-far too slow to keep the company in the game. The problem with the account, which strives hard to present Elop as a considerate CEO with few remaining options besides turning to Microsoft, is two-fold. Absolutely, Nokia needed a shake-up, but Lou Gerstner faced simiar challenges at IBM in the early 90s and solved it by improving cross-company collaboration, reorganising the business and cutting swathes of middle managers. This, combined with the resulting cost savings from cutting headcount, should've meant Nokia were able to release three high-end MeeGo devices by the end of 2013; with Symbian filling in the featurephone market below it.
Ignoring iPod Touches, Apple release 2 iOS devices a year: a phone and a tablet; often with relatively minor improvements over the previous year's model. It's hard to believe that this business model around MeeGo devices couldn't have been similarly successful for Nokia. The organisation and pigeon-holing of devices into N-series for multimedia or E-series for business is the business organisation that needed to be addressed. The iPhone can do multimedia and busines requirements equally well, why couldn't a single MeeGo device from Nokia?
Elop's solution of going to another company to provide their platform fails to address the core issues plaguing Nokia that prevent them from being competitive in the market (namely middle-management bloat and incompetence; a multitude of confusing, unfocused compromise devices; and the inability to ship a quality platform). While, arguably, moving to Microsoft as the platform provider enables Nokia to focus on the hardware that has always been their strong poin; hitching themselves to what's currently not a winning horse (nor likely to be) while eliminating much of their differentiation potential isn't likely to put them in a good position.