I was recently working on porting a Silverlight for Windows Embedded demo from Windows CE 6.0 R3 to Compact 7 and the project which was using ATL wouldn’t compile, stating that some ATL headers were referencing some unknown constants…

There actually is an update to ATL that has just been published and that needs to be applied to ensure a Visual Studio 2008 SP1 smart device projects compile and work on Windows Embedded Compact 7 . You can download the update from here.