John Mayor & Taylor Swift

Taylor Swift's latest album is shaping up to be an open book about her love life. First she penned a song about 'Twilight' hunk Taylor Lautner. Now, she's reportedly taking aim at John Mayer, which confirms rumors that the two were romantically involved in 2009 while collaborating on 'Half of My Heart,' a track from his last album. Based on lyrics from Swift's new song 'Dear John,' off her forthcoming 'Speak Now,' Mayer broke her heart.