Nokia CEO Stephen Elop

It looks increasingly likely that Microsoft's Windows Phone 7 will get a starring role in Nokia Chief Executive Stephen Elop's attempt to turn around the ailing phone giant.

Reports from Bloomberg and The Wall Street Journal indicate Nokia's turnaround plan will involve phones using Microsoft's new and still immature mobile operating system. Elop plans to detail his strategy for overhauling Nokia tomorrow at an analyst day in London.

Google's Android, another contender for a software alliance, doesn't look like it has good prospects at Nokia at present. "Two turkeys do not make an Eagle," tweeted Vic Gundotra, vice president of engineering at Google, including a "feb11" hashtag to make it clear he was referring to Nokia's event on that date.

Elop, who arrived from Microsoft to take over Nokia a few months ago, offered a scathing assessment of Nokia's phone strategy thus far. In his "burning platform" memo, he said Nokia failed to answer Apple's iPhone at the high end, respond to Google's Android operating system spreading to the midrange and lower-end smartphones, or stem the tide of inexpensive Chinese phones. And its own operating systems are a mess, with Symbian not up to the modern smartphone challenge and the higher-end MeeGo only just dipping its toes into the waters with a single phone coming late in 2011.

It's easier for an outsider to be brutally honest, of course--especially when it's all part of a campaign to pave the way for the would-be answer. Elop plans to deliver that half of the speech tomorrow.

An alliance with Microsoft makes sense at one level: both companies are powerful but at a serious disadvantage to incumbent players--Apple, Google, and a host of phone makers including HTC, Samsung, Motorola, Sony, and LG Electronics that have embraced Android.

Nokia has clout in the mobile market--deep relations with carriers and phone retailers, for example. And Microsoft has clout with developers. An alliance between the companies could convince developers that Windows Phone 7 is more likely to get the critical mass needed to justify writing software.

But it's no slam dunk. Windows Phone 7 is already a late arrival, and it's not clear how many application ecosystems developers want to support. And unlike Android and iOS, it doesn't span to the tablet level, where Microsoft prefers its older Windows ecosystem.

Relying on another company's operating system yields a lot of control of the ecosystem to that company, as countless Windows PC companies and Android phone makers know. Apple has a great deal more control over its destiny with its own integrated hardware and software for mobile devices--control that's nice as long as you have a relevant ecosystem developers are eager to sign up for.

Nokia still has that possibility of unified hardware and software with MeeGo, of course. But the more serious its commitment to Windows Phone 7--and thus the more likely that initiative will be to succeed--the harder it will be to convince developers to later add MeeGo to the mix.