This string is called The Oracle because it tries to guess informations from various sources (filename, directory name and other tags).
It shows 'guessed' values in dark blue, this is very convenient to quickly see which songs are well-tagged and which one aren't.
It also includes current playing, bitrate gradient and Replaygain values (absolute !)

Last version at http://www.atomas.com/foobar/

Look at the playlist start comments for more infos.