I haven't stopped laughing yet...
Images of 2 drunks propping each other up or 2 dinosaurs looking anxiously at the skies come to mind!
Nokia's problems stem from being unable to bring to market good engineering and design ideas with sufficient speed, neither of which will be significantly helped by trying to use Windows.
Micosoft's problems stem from having built a paranoid, inward-looking software empire that produces mediocre products slowly and fosters developer interest through fear rather than enthusiasm. Their prospects may be marginally improved by this announcement, but as long as they are unable to change their corporate culture ( leap off THEIR burning platform, if you will ), they will continue to be an also-ran in new makets.
I thought Meego had been too long in gestation to garner much support, but at least it was a move in sync with the general trend towards *nix based and open development models; looking backwards towards Microsoft seems poor judgement.
From a developer point of view, I want to construct my toolset around what makes most sense to me, picking and choosing what is best for my requirements. Both Symbian and Windows ( for different reasons ) make this difficult, and therefore are unattractive.
From a user point of view, I want a wide selection of different device experiences to choose from. Most people grow up with rapidly-changing technology now, and are quite able to learn any interface that is put in front of them.
From this point of view, Android has it right in that the underlying platform is a consistent ecosystem, but the interface can reflect the needs of the device it is running on, or the market the device is aimed at. Windows Mobile, on the other hand. has just returned to the Microsoft dark ages of preventing differentiation and providing a one-size-fits-nobody experience. No thanks.
Nokia probably should have chosen to go with some combination of Meego, Android and maybe even talked to Mark Shuttleworth at Canonical ( Ubuntu ) for their software needs, whilst getting their head round the challenge of resolving their design and engineering problems.
When it comes down to it though, Nokia are a big company that want control ( look at how their behaviour destroyed the promise of Symbian ) and Microsoft are a big company that want control. There will be tears before bedtime...