Recent interviews, as well as leaked developer docs for Microsoft’s Windows Phone 7 Series help put together some interesting pieces of the puzzle left in the wake of the Mobile World Congress announcement a few days back. A few of those questions included multitasking, backwards compatibility and partner customizations. It’s clear in the documentation that WP7S will be capable of multitasking, both full background applications and a background notification system. Although the functionality does exist, to what extent can developers make use of it is another matter.

Also, as for development tools, Silverlight, XNA (used by Zune and Xbox devs), and .NET CF are all available. Although Silverlight and XNA are new to the phone platform, .NET has been a Windows Mobile staple for quite a long time. Both these docs, and a recent interview over at tweakers.net with Maarten Sonneveld of Microsoft Netherlands, basically confirm that although current applications won’t run on the new phones, it’s more a matter of tweaking for the new UI than anything else. There are some debates whether the translation is entirely clear, so the issue of easy conversion is not entirely clear.

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Applications that were made for Windows Mobile 6 are compatible with Windows Phone 7 Series. The interface of the new mobile operating system has been changed though, so the user interface for these applications will have to be changed as well.
“So there is no reason why programs written for Windows Mobile 6 cannot run on the new version of the OS”, said Maarten Sonneveld of Microsoft Netherlands to Tweakers.net. “The interface is complete different though, so the applications will have to be changed somewhat before being ready for Windows Phone 7 Series”.
It is still unclear how developers can port their user interfaces to the new version of Windows Mobile. Microsoft will only disclose how applications can be developed and distributed at their developer event Mix2010.
Microsoft announced it’s new OS on Monday afternoon at the Mobile World Congress in Barcelona. The OS is primarily aimed at synchronisation and integration with Microsft-services like Windows Live, Bing, Zune and Xbox Live. Aside from those Windows Phone 7 Series can also synchronise with Google-accounts and facebook. [tweakers.net via WMPoweruser]

One element of these docs that seems to be largely overlooked is that MS will allow hardware partners to access the system at a deeper level than independent developers. This would theoretically allow a manufacturer such as HTC or Samsung to create their own custom ‘experiences’ on the phone. In the past, partners would create their own custom GUIs as they saw fit, but moving forward, Microsoft will have a hand in approving any such changes. For example, take HTC’s Sense UI, which is available on both Windows Mobile 6.x and Google Android devices. Right now, HTC doesn’t need approval for making Sense. They just put it on their devices. In the Windows Phone 7 world, it appears that Microsoft will have a more direct say in such changes, which seems in line with their policy of taking a much more hands on approach to devices, instead of handing out OS licenses to anyone with $20 in their pocket.

Although I wouldn’t expect any heavily customized UIs out of the gate, we probably will be seeing Sense UI for WP7S at some point.

Also, there were some rumours that the sample Windows Phone device at MWC was made by Asus. The below video from Slashgear has a Microsoft rep confirming it, right at the beginning.