Last April, President Bush’s iPod lineup was revealed to the world to contain some rather incongruous choices – from “My Sharona” by the Knack to a few Joni Mitchell songs. The world shrugged. But apparently what the leader of the free world is listening to is still a burning question, and so the Post’s Reliable Source today reports that Bush’s iPod Shuffle is now filled with some different tunes – everything from “American Pie”…