We'd heard the Nokia Lumia 900 was set to go on sale April 8th, and now it looks like you can circle that date on your calendar with something a little more permanent: according to WPCentral, the flagship handset will be available online beginning the 8th, and in stores one day later. The Windows Phone handset that so intrigues our own Chris Ziegler will apparently cost $99 (with a two-year contract, of course), and we've heard it will also come with a Microsoft-supplied app card and a huge blitz of marketing from both Microsoft and AT&T. According to WPCentral's tipster, the phone is even already shipping to some AT&T stores. Nokia hasn't officially confirmed the phone's launch date, but all signs point to the second week in April.