On the site, she also posts the following explanation --
"I have known Joe Gordon-Levitt for going on 12 years. We first met in the summer of 2000 while doing a tiny movie called Manic, where we bonded over a mutual appreciation for Harry Nilsson and Nina Simone and I have been lucky enough to call him one of my dearest friends ever since. When we did 500 Days of Summer 8 years later, we spent every lunch hour dancing to Marvin Gaye in the hair and make up trailer; we had loads of fun. I hope to do a thousand more movies with him because he's simply the best. But in the meantime, we made a little New Year's duet for all of you! The original by Nancy Wilson. ENJOY!"
For the sake of accuracy, she's wrong about a couple of things. For starters, it is not "by" Nancy Wilson. Yes, I know she (like many singers) is referring to who recorded it, but who a song is "by" is personal bugaboo of mine. And it's especially notable here because this particular song was written by the great Broadway composer Frank Loesser (who wrote Guys & Dolls and How to Succeed in Business Without Really Trying, among others), though it wasn't for any show or movie, just a standalone song.
She's also wrong that the original was not recorded by Nancy Wilson, missing by almost two decades. The original recording was performed by Margaret Whiting in 1947. (Wilson didn't record it until 1965, though she had a big hit with it, reaching #17 on the Billboard charts.)
But those are details. The performance itself is the lovely point of it all --