Boxcar Developer Push service was recently updated to support Google Cloud Messaging 3.0 (GCM 3).
Google changed the semantic of the identifier. They replaced the ad-hoc RegistrationID with a new Universal Identifier. Android Developer will need need our new Boxcar Android SDK 3.0 to support it.
You can find more details on Boxcar Developer Blog: New Boxcar Android SDK 3.0.0 and SDK 2.0.4 released