This is a big milestone in Microsoft’s revamped mobile platform strategy and roadmap. As OEMs and service providers add their final touches to WP7 devices, consumers can expect the devices during the holiday season.

Terry Myerson, Microsoft's corporate vice president of Windows Phone Engineering, writes in his recent blog post:

Windows Phone 7 is the most thoroughly tested mobile platform Microsoft has ever released.  We had nearly ten thousand devices running automated tests daily, over a half million hours of active self-hosting use, over three and a half million hours of stress test passes, and eight and a half million hours of fully automated test passes.  We’ve had thousands of independent software vendors and early adopters testing our software and giving us great feedback. We are ready.

You can read the detail of his post here.