So I'm aware that C2DM is deprecated and that we eventually have to switch to GCM, but I wasn't expecting them to kill it off just yet.
My application is currently using C2DM, which is still working fine on devices running Android 2.3 etc. Even when the application has been completely terminated.
However, on ICS, C2DM messages does not arrive at all when you terminate the app.
The Google Cloud To Device messaging service does not longer show up under the running "Google Services".
Does anyone have any official information about the removal of the C2DM service process in ICS?
Is the only solution to move over to GCM if we want the device to receive messages when the app isn't running?
Yes, you will have to move over to GCM. However, it is possible to have both CD2M and GCM active while your clients are updating.
From your server-side application, you must keep keep track of whether a registration ID is from C2DM or GCM and use the proper endpoint.
You can find more information about how to properly migrate from CD2M to GCM here: http://developer.android.com/guide/google/gcm/c2dm.html