I managed to get a prototype with JSF2 get working at Googles AppEngine following this tutorial. Now I have some odd behavior with a ViewScoped ManagedBean:
Normally I don't answer my questions and I only rate this answer as a workaround and not as the correct answer. Event if I don't like client state saving, this seems to fix the odd behavior. But I have to check this in detail:
javax.faces.STATE_SAVING_METHOD
client
Perhaps we should wait until JAVASERVERFACES-1886 is resolved.