It is referring to High End machines he will announce monday. And i beilive he is referring to G4 Apple's Macs not G5 anyway, also because top PPC line from Apple is QUAD CORE G5 (2 dual core).
I tried to export some files from my iTunes (mp3 and mp4) and i see that the information like album and artist are not displaying right in Tunenet... i really think Tunenet should use same format as iTunes...