Which would normally be more a matter of my lack of pop-culture knowledge than something relevant to words or language. Except that the phrase seems to be suddenly becoming a popular metaphor.
I saw it in two different news stories during one week a couple weeks ago. I didn't record the first, but the second is a New York Times article, "The Fall and Rise of Media," which says (about job loss in traditional media) "That carnage has left behind an island of misfit toys."
It's possible this has always been used as a metaphor, ever since the Rudolph TV special was broadcast in 1964, and I just didn't notice it until I had a referent to pin it to. But I see that a direct-to-video movie, Rudolph the Red-Nosed Reindeer and the Island of Misfit Toys, was released in 2001, and has been aired annually on ABC since December of 2006, so I'm speculating that that's led to increased awareness of the Island. I don't have time to track the phrase further, but I suspect use of the metaphor has gone way up in the past three years.