I'm trying to migrate from C2DM to GCM, and it mostly works just fine. C2DM used to handle uninstalls of the app very well by sending a NotRegistered error when the user uninstalled the app. GCM supposedly does this as well (albeit not guaranteed). However, it doesn't seem to be working. After sending multiple GCM notifications to a phone which has uninstalled the app, it still keeps responding with a normal "id=..." response.
Has anyone else come across this problem? If so, how did you solve it?
There's really nothing we can do about it. Only Google knows when an app is uninstalled and update their device registration database accordingly. Perhaps it takes a couple of hours for NotRegistered response to come back? If after a day, you're still not getting that, then file a bug report with them: http://code.google.com/p/android/issues/list
I can't imagine Google will let this bug stay for too long, as they are potentially looking at sending phantom notifications to thousands or hundred thousands of devices.