Sony's game lineup really only sells to people who already have a PS3.
Their PS2 lineup was different because they had products like Singstar, Buzz, Eye Toy, Ratchet, Jak etc.. which were unlike anything else available elsewhere.
Now Nintendo has taken their social gaming, Microsoft took their core gaming segment, and now they've only got a price drop left to spike interest. Which it should do quite well, but leaving it this late really makes things tough