Can Windows Phone 7 run apps with the screen off?

Running third-party apps on a smartphone with the screen turned off may seem like a no-brainer to those using an iPhone, BlackBerry or Android device. But as usual, Microsoft is quite (unfashionably) late to the party.

Yes, indeed, Redmond has magnanimously decided that WP7 applications will now be permitted to run on screen-locked phones – without requiring special permission from harried and clueless users.

Of course, developers must first prove to Microsoft that the app sips a “reasonable” amount of battery power, i.e., no more than six hours of use for an application playing audio and 120 hours for a program that does not stream audio.

As CNET’s Ina Fried points out, the rather tardy policy adjustment is clearly a matter of both convenience and fairness.

“Some developers have complained that MS allows only certain tasks to run in the background and also that its applications do things that third-party programs cannot.

“[For example], background music playing is one such feature, while another is direct control of the camera for tasks beyond basic image capture. [Naturally], many of Microsoft’s own apps – including application downloading, e-mail syncing, and Zune playback and downloads – are all allowed to happen in the background.”