I don't know if this is already on this thread, but George Martin produced an album of his own,
In My Life, which consisted of other artists covering Beatles tunes. That was in 1998.
It's an "interesting" album, in that you have people like Robin Williams, Goldie Hawn and Jim Carrey covering songs - plus Sean Connery doing a spoken-word "In My Life." There are some great tracks on there, though - John Williams' classical rendition of "Here Comes The Sun," Jeff Beck's instrumental "A Day In The Life," and Phil Collins does a pretty good job on "Golden Slumbers/You Never Give Me Your Money/The End." And, to be honest, Jim Carrey's take on "Walrus" is actually pretty cool.
Don't know if that counts as pop. He also produced the Broadway version of "The Who's Tommy" in 1993.