On John Mayer's twitter (twitter.com/johncmayer), John says:

"Waking up to this song idea that won't leave my head. 3 days straight now. That means it's good enough to finish.' 'It's called "Half of My Heart" and I want to sing it with Taylor Swift. She would make a killer 'Nick in contrast to my 'Petty' of a song."

Hmm, what do you think? Do you think it will actually happen?

I hope so, I think the song would be awesome!

I guess only time will tell!