Both XM Canada and Sirius Canada Iphone OS 4 App's do not work in background. I upgraded my 3GS phone to the new O/S 4.0 software tonight. One of the features is you can listen to third party music while you multi-task, Previously you could only do this with the Ipod feature of the IPhone. After downloading the new software I tested both Sirius Canada and XM Canada's official App and they did not work in the background. I then tried Pocket Tunes and surprisingly that worked for Sirius (I presume XM would work as well). I also tried the Major league baseball App and it also works in the background. Therefore Sirius Canada and XM Canada have some woirk to do to get this fixed. Especially XM which is charging $2.99 a month.