Well, maybe Reeves really is talking about software emulation of PS2 titles. But it seems more likely he's talking about the PS3/PS2 disc swap compatibility for Singstar. With a PS3 version of Singstar you'll be able to disc swap to a PS2 version and play those songs:
http://blog.us.playstation.com/2008/...compatibility/
This isn't so much emulation of a PS2 title as it is PS3 Singstar being able to read the game data from older versions of itself.