Great response!!! And, yes K, it sounds beautiful chanted in Greek, as well as in Latin :-) I still have happy memories from 2 years ago when a Maronite monk was canonized and the Gospel was chanted by a RC deacon in Latin, then by a Maronite priest, in Arabic.
I believe the Pope uses these events to remind Catholics that the Church is both Western and Eastern. This is the first time, however, that the Vatican choir chanted the responses in Greek. That speaks volumes about the Pope's seriousness in conveying this message.
Maybe that is one of the reasons Benedict XVI wants to free the traditional Latin Mass. It does contain Latin AND Greek. ;-) At all high Masses the choir (and the congregation) chants the Kyrie.