Justin Bieber may be dating Selena Gomez, but he's written a song with her good friend Taylor Swift. Producer Kuk Harrell, who has worked with Beyonce and Rihanna to craft some major pop smash hits, spilled the beans about this meeting of musical minds. Harrell tweeted about the collaboration, which could be an epic hit, given the popularity, talent and overall star power of both Swift and Bieber.

Earlier today, Harrell tweeted, "Wow!! Got to see @justinbieber & @taylorswift13 write a song together last night!! SMASH!!!! SMASH!!! SMASH!!! Let's do it again Yall!!!" Bieber then re-tweeted that post, lending credence to the news.

On Friday night, Bieber even posted a short (and not very informative) tweet which read as follows: "#writing." That cryptic message makes more sense in light of Harrell's tweet. For her part, Swift has not yet tweeted anything to confirm that she engaged in a writing or studio session with Bieber, but fans have responded eagerly by making "Justin and Taylor" a trending topic on Twitter.

Bieber joined Swift onstage at the Staples Center in Los Angeles on August 23. They performed his song 'Baby' together, and fans of both were pleased to see them sing together -- and the seeds of a possible partnership were already sown. Now, we have an inkling of what they are like together in a professional capacity.

Swift did tweet about how awesome it was to duet with Bieber. She posted: "You think you've heard LOUD screaming in your life.. Then @justinbieber comes out and does a surprise song during your show. Woah. Unreal."

We are anxious to hear the fruits of a Swift-Bieber collaboration.