Kotaku that the PSP version of LittleBigPlanet (what, you didn't hear?) would feature the same pillars of the PS3 game -- play, create and share. Also, director of hardware marketing for SCEA John Koller added, the little LBP might work with the PS3 version in some way, possibly with level sharing, but nothing is set in stone.
Now, don't get mad at us if Koller means you'll be creating carts, playing with carts in races and sharing carts with friends, but it sounds like you can be a little more relaxed about LBP's portable future.
Additionally, Koller assured that LBP and the rest of this week's PlayStation Destination announcements only represent a portion of the year's handheld lineup, teasing that "some fairly major, triple-A titles are coming for the back half of the year that are going to be announced in the coming months and at E3."