Although the fine folks over at Boy Genius Report (where I first heard this rumor) believe that it is a stretch at best, Paul at Windows Phone Secrets reports that he has glimpsed Microsoft’s upcoming “Mango” update for Windows Phone 7. During a video walk through of a NoDo update. Around 2 minutes and 48 seconds into the video, the cameraman pans to a second Windows Phone 7 device for a few seconds. This second phone has a feature never seen in current builds of Microsoft’s mobile operating system: Inside the main menu, there’s a clearly visible search button.

Is this Mango? My sources are not sure, and neither am I, but we do know that it’s an option that’s not currently available in the latest NoDo update.So Microsoft either has another minor update in store, or someone spotted Mango. Microsoft is expected to launch Mango later this year, and it should include Internet Explorer 9, the faster Trident 5 rendering engine, HTML 5 support, Silverlight, and gestures. A release date is not yet known, but a set of features like that will go a long way toward cutting into Android and iOS’ ever increasing market share.