When Nokia (NYSE: NOK) unveiled its new flagship smartphone earlier this month, the Lumia 920, there was one glaring detail omitted: its release date. The device is an incredibly important step for Nokia's turnaround and transition as its first Microsoft (Nasdaq: MSFT) Windows Phone 8 device, yet it declined to say when consumers could even get their hands on the device.

According to a recent report from The Verge, the culprit isn't Nokia, but rather its better half -- Microsoft. Windows Phone 8 isn't ready yet.

The software giant had been originally targeting an early October release, but this has been pushed back slightly as Mr. Softy puts the finishing touches on. There have been various bugs that have needed to be addressed, causing delays that are hindering OEM partners like Nokia. Microsoft has reportedly told other partners, including Samsung and HTC, not to demonstrate the operating system, even though Samsung also recently unveiled a Windows Phone 8 device before Nokia did.

That's why at Nokia's event the media wasn't allowed to actually handle the devices, because the OS simply isn't ready yet. Nokia has announced that it will be available in the U.K. with LTE support exclusively on local carrier EE, but there are still no pricing or availability details quite yet.

Nokia has a lot more riding on Windows Phone 8 than Microsoft itself does, since it's the OS platform that the struggling smartphone maker has gone all-in on, contrary to its prior statements about having some unknown "contingency plan." It's naturally very important for Microsoft in many ways, but not as much financially. Smartphones were 20% of Nokia's business last quarter, while Windows Phone was well under 10% of Microsoft's.

Microsoft had better hurry up, because Nokia is anxiously awaiting its OS savior.

Fortunately for Microsoft, its other cash cows continue to generate plenty of operating cash flow. Check out The Motley Fool's premium report on Microsoft, which lays out the bear and bull cases for the tech giant. Sign up today and get free updates for a year -- all at no extra cost to you!

Fool contributor Evan Niu holds no position in any company mentioned. Check out his holdings and a short bio. The Motley Fool owns shares of Microsoft. Motley Fool newsletter services have recommended buying shares of Microsoft and creating a synthetic covered call position in Microsoft. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days. The Motley Fool has a disclosure policy.