Actually I think everyone has given valid examples of how the term is used, as well as valid definitions.
I see little to debate, and see very little difference in all presented. Be it a song or poem, your prosodic efforts will be based upon the same elements, with the only exception being that prosody in lyrics will include notes/tones/semi-tones. Volume, accent,timing, rhyme, & rhythm apply equally to both...eh? what say ye?

-gary