While Microsoft has lifted the lid on its ground-breaking new Windows Phone 7 Series operating system and demoed it extensively at Mobile World Congress 2010, there are still a few questions left unanswered about the new smartphone OS.

Microsoft's MIX developer event in March should address many of the outsanding questions about the platform, and others will no doubt be resolved over the nine months before the first Windows Phone 7 Series devices begin appearing in stores.

Right now though, here are a few we've been wondering about:

1. Will it have real multitasking?
   So far Microsoft hasn't exactly been specific when it describes how Windows Phone 7 Series devices will deal with running multiple applications, something existing Windows Phone users (as well as other smartphone platform users) view as a necessity. Just because the iPhone doesn't support multitasking yet for third-party apps, doesn't mean consumers don't want it. Full multitasking capabilities are expected to be covered at MIX of course, but we won't rest easy until we hear it from the horse's mouth. Why hasn't Microsoft covered multitasking yet? Well, Microsoft needs something to reinvigorate blogs and media between now and December, doesn't it?
2. How much can controls be customized?
   With a dedicated physical button for Bing on the spec requirements, there doesn't look like much scope for using your own choice for default search engine. Is Microsoft going to allow other search engines to get a front row seat on its Windows Phone 7 Series-powered devices, should the user want to swap?
3. Will Windows Phone 7 Series offer any Mac support?
   Can Microsoft get its device into the right hands of trend-setting early adopters without making some concessions here? The iPhone-toting, Mac-owning users would be infinitely more likely to get onboard the 7 train if a decent level of Mac support was there right out of the box.
4. Will there be enough new apps at launch?
   Microsoft hasn't yet revealed anything firm about SDKs, developer policies or how applications might be restricted. Getting up to the mark in the application numbers game may be tricky, particularly with demands on developers' time and resources from multiple smartphone platforms. We're sure Microsoft has plans for boosting its application arsenal -- and we're sure to hear more at the MIX event.
5. What do we do with old Windows Phone apps?
   Starting from scratch with a ground-up new operating system, Microsoft seems to have jettisoned the baggage of having to accommodate older software in high-powered new devices. But what about its loyal customers who've stuck by Microsoft smartphones through thick and thin? Particularly corporate customers for whom Windows Mobile was the fleet mobile device of choice. Any chance of an upgrade path or some credits?
6. How good will the Xbox LIVE experience be?
   The iPhone has shown how impressive gaming can be on a large touchscreen device, and the promise of Xbox LIVE support will surely grab huge gamer interest. But can Windows Phone 7 Series really deliver a gaming experience that will be exciting enough to live up to expectations? If it can, it could be a real winning feature.
7. Has Microsoft left it too late?
   We're all just going to have to wait and see. By the end of 2010 when the first generation of Windows Phone 7 Series devices hit the stores, the next generations of iPhones, Android devices, Symbian smartphones and others could well match the great ideas we're now seeing in Windows Phone 7 Series. Could the wow factor have waned by the time real products are in the stores, or will new Windows Phones end up as the must-have gadgets for this year's holiday season?

Originally published by our UK sister site, Know Your Mobile