XDA Developers has just released a document that confirms that Windows Phone 7 OS does  multitask however still no word if there is third party app support.

“Windows Phone OS 7.0 support multiple processes running simultaneously on the system.”

Source Windows Phone 7 development docs leaked

Gizmodo asked the really hard question from Microsoft about weather Windows Phone 7 is a multi-task phone and the answer pretty much a text book copy of Apple’s answer.

"The core operating system is a modern multitasking operating system. If you play music for example, the music will play back as you navigate around the experience…if you’re using email, we have great support for push email and that happens in the background.

For third party applications—we’ll get into a lot more detail on this in MIX—but we have a few ways we’re going to make sure that third parties can bring their value to the user even when the app is not running. Live tiles are an example. Data feeds in the hubs are another example for some apps.”

Hopefully the answer will be more clear at the MIX developers conference next month.

Source Is There App Multitasking in Windows Phone 7? (Hint: It’s a Lot Like the iPhone) – windows phone 7 series – Gizmodo