The most famous (or infamous) radio play from days gone by is probably the War of the Worlds production by Orson Welles. Some listeners apparently thought it was real, and panicked at the idea of an alien invasion in New Jersey.
In later years, television would come to replace radio as the medium of choice for broadcast entertainment, and the radio play disappeared from the collective consciousness. For someone like me, born in the 1970's, it's simply a historical footnote, and one I probably wouldn't have learned about at all if not for the infamous War of the Worlds broadcast.
But things seem to be coming full-circle now. The advent of digital self-publishing has also led to the self-recording of audiobooks, and with that, we are seeing a return to the good old-fashioned radio play of yore.
Hugh Howey gives us an example here. I find it interesting that the story was adapted for the first-person POV. Hugh wrote Wool in third-person.
Baen Books is on the radio bandwagon, too.
It's an exciting time to be an author. A little too exciting, actually; everything changes so fast, and it's hard for me to keep up. What worked six months ago is passé now. I guess we all just have to do the best we can and try not to get swept away.
In the meantime, though, I'm enjoying the return of the radio play. It's like a piece of Americana from the 1930's, reinvigorated for a new century, and I think that's awesome.