Here’s an interesting development, it looks like AT&T and Microsoft will be holding a Windows Phone 7 event on October 11. Despite Microsoft’s own website billing the “Worldwide Launch Event” for 3:00 PM on October 11 with T-Mobile in tow, we’ve just been sent an invitation to a 9:30 AM October 11th event; complete with appearances by Microsoft CEO Steve Ballmer and AT&T CEO Ralph de la Vega. Looks like AT&T may be the exclusive launch partner for Windows Phone 7 after all… even if it is only for a few hours.