If the iPhone is the reason, it doesn't make any sense T-Mobile would want to merge with AT&T. Now that the AT&T exclusive to iPhone is over, now is when iPhone-iacs will be moving away from AT&T. Why would T-Mobile eliminate themselves as an option for the hordes looking to get away from AT&T?

Matthew MacDonald has been doing Silverlight books since version 1.0. I own his C# flavor of this 4.0 book. He's one of those authors that waits until a new technology has soaked in a bit, his book reflects that (as opposed to getting the book out their as soon as 4.0 was released). This book came out about 4 or 5 months after Silverlight 4.0 was released.