a and b were inevitable from where I'm sitting. Symbian is dropping like a rock, and MeeGo would have a very difficult time coming into the market if all Nokia could manage is one product later this year. So the change to something more established seems like a good call. This would always require change, so c is pretty much tied to a and b.

d is the only one where I think Nokia has to be really careful, as it could easily lose too much control to Microsoft, but it seems they have a special deal going with them with what they're allowed and not allowed to do with the OS. 

So all in all, a risky move, but one I think will produce good results, and certainly better results than MeeGo or Symbian would have got them going forward.

Interesting choice.  I guess Nokia had a choice of going with a - currently - more popular OS like Android but having to compete as part of a very successful pack of companies (Samsung, etc) or taking an approach based on differentiation with a partner capable of expending a lot of money to attain success.

I see this as the risker option but the one that, if it pans out, could bring them better benefits overall.

I think it is a riskier choice though.  Should be interesting to see how it pans out.

i would like to point out that nokia would be getting an heathly check from MS.

Also whats the difference nokia is going to get from sony, htc etc windows 7 phones other than phone design which nowdays doesn't matter since they are all one big screen on an small case. 

I think the fact that Nokia shares instantly dropped by about 10% after this decision was announced makes pretty clear what to think about that alliance.

I wonder how Microsoft managed to convice Nokia though, as it's pretty obvious that Microsoft will benefit from this alliance while Nokia will suffer. Did Microsoft give Nokia some of their 500 million WP7 marketing budget?

Both win benefit... i think you need to read the OP

Nokia made the right decision here.

Having them hop on the Android train would put them in direct competition with the likes of Samsung and Sony... Those companies make their own OLED screens and processors and such and have sinergies with other tech aspects. Dollar for dollar and feature for feature, Nokia can't directly compete with them as all they do is make phones. Nokia has always been unique in its approach and this allows them to do this. Not many people have seen/used this Windows Phone 7 OS yet and while it has some bugs to fix, it is extremely intuitive and is pretty much mass market ready.

Whats amazing is the level of aliance that the companies will share -

Microsoft's Bing and adCenter will provide search and ad services across Nokia devices, while Nokia will look to innovate "on top of the platform" with things like its traditional strength in imaging. Ovi Maps will be a core part of Microsoft's mapping services and will be integrated with Bing, while Nokia's content store will be integrated into (read: assimilated by) Microsoft's Marketplace. Xbox Live and Office will also, as is to be expected, feature on these brave new Microkia handsets.

Surely some economic incentives, but they also offered a competitive edge in the WP7 submarket: they granted Nokia the right to customizations they denied to HTC, even though Elop was quick to point out that they will stay pretty close upstream. Obviously that also entails that differently from HTC Nokia will be using WP7 exclusively.

For MS it's a big win, as adoption of WP7 has been much less than brilliant and they need models out there. For Nokia it's a chance to be the biggest name in the third OS submarket for smart phones, and to finally cut and refocus their enormous R&D expenses. Basically looks like the preamble to an acquisition to me.

No, but if the desktop versions of Windows are any indication of MS's capability to develop working software (the desktop versions are slow and somewhat unstable - true, no huge crashes anymore but I think I notice more or less annoying glitches every week or so). And more importantly, I don't like the way MS handles things.

Anyway, I can't afford getting a new phone that often so even if I wanted, I doubt I could try every OS I wanted to. But personally I think Android is the future (and the present) right now, and I also look forward to MeeGo (though not so much after this announcement anymore).

I think reading some of the comments here it is almost like the console wars extend to anything Microsoft do. I would suggest before you slag off the WM7 you actually try and spend some time with it. I have found it to be very competent, some niggles for example the lack of a weekly calendar view and no out of office support but these points aside it is now my OS of choice even over Android. The first update is expected this month with some performance improvements and the obligatory Cut and Paste add on.

They really need to work on their business side of WM7. Its mindboggling that they have the user experience, and entertainment side down...but they kind of dropped the ball on the business side with the things you mentioned it lacks. It also doesn't have Microsoft Exchange integration yet...thats rediculous. Windows Mobile 1.0 had this...