Mega animation company Pixar has a long history of teasing characters for their upcoming movies as an Easter egg in their current film. For example if you’re paying attention, you can catch Nemo, from Finding Nemo in Monsters, Inc.. They’ve done it again with Up, this time they’re teasing a brand new character which you’ll see in Toy Story 3.
The shot in question is actually in the very first teaser trailer for Up. The picture below is a closeup of everything under her bed in that teaser, during the scene in question. There are only three things under her bed. The first item to the right appears to be a chapstick, the item in the middle sort of looks like a pair of old slippers. Then there’s a rather cute, plush teddy bear. Is it the teddy bear? Is that Toy Story 3’s new character?