Christ is Risen!
As in most things in Orthodoxy, it depends upon one's bishop and jurisdiction. For example, in Greece, not all priests are allowed to give sermons and "learned laypeople" have, at least in the past, been allowed to give homilies. From my experience in North America, it is normally reserved for the priest, maybe the deacon, and in special circumstances, a layman. When in doubt, ask your bishop.
Basil