It's been reported that Leighton Meester fan site LeightonSource.org said that Leighton Meester of Gossip Girls has already recorded a duet with Justin and that the song will be released later this month. They even quoted Justin as saying "It's a ballad with great harmony and very romantic lyrics, something unexpected but amazing."
This is the first I've ever heard of this news. I think if they have already recorded a song together we would probably hear this news a long time ago. I went to the fan site to look for the post and I cannot find it anywhere. It does not help that the site is all in Spanish. =/
No title for the song was reported and a search on Google came up absolutely nothing so I'm going to have to file this one strictly under rumor.
Anyone know if there is any truth to this? Please share if you do.