With the release of Android Studio 1.0 Google has declared AS to be the official IDE for Android (see the announcement here), signalling the beginning of the end for Eclipse/ADT support.
I have Java projects in Eclipse that use both ADT and GPE: corresponding client and server projects which share code. So I will eventually need to switch to AS, and will want to switch both my ADT and GPE projects at the same time, but I could go quickly (to get the benefits of AS when developing for Android), or only move when I have to because I like Eclipse and am unsure of the degree to which AS/IntelliJ replace GPE.
So, my question is, what is the status of GPE for Eclipse, and to what degree is GPE functionality supported in AS? Is Google cloud team still actively developing GPE (beyond necessary stuff like support for Luna)?
Echoing Branflake2267, GPE is still under active development. It slowed down for a while as there was a change in teams and staffing. Development is now picking up.
You can expect that GPE will continue to support Cloud-related features just as they will be supported in Android Studio. Features related to Android + Cloud integration will appear in Android Studio as opposed to GPE, as the Android Tooling in Eclipse (ADT) will no longer have parity with the feature set in Android Studio.