1up considers the curious case of Little Big Planet and its disappointing sales numbers.

...you have to wonder how a game like Little Big Planet would have faired [sic] if it had launched during some of the slower months earlier this year.

You also have to wonder how it would have fared if it had been more of a game than a level building toy box (although that didn't seem to hurt Spore). But mostly, you have to wonder how it would have fared if it weren't limited to the install base of the Playstation 3.