Eric Whitacre wrote this music to fit the poem "Stopping by Woods on a Snowy Evening" by Robert Frost. Rather stupidly, Robert Frost's estate told him that he couldn't use it until it becomes public domain in 2038.
So he asked Charles Anthony Silvestri to write a new poem to fit, using the same meter and some of the same words... this is the result:
The whole virtual choir thing is pretty darn awesome, too.
(Hat tip to @elmyra who brought the post on BoingBoing to my attention.)