JOHN MAYER has spent most of the past two years dealing with some throat problems . . . but apparently, he's well enough to return to the road, because he's announced a big summer tour with Phillip Phillps!

 NELLYjoined TAYLOR SWIFT on stage at her concert in St. Louis . . . and they performed his song "Hey Porsche".  That’s the thing about aTaylor Swift show..you never know who’s going to show up on stage and perform a number with her! 

  Joe Jonas did NOT record a raunchy playin the piano tape with his Swiss model GF ...