Briefly: I thought it was worth mentioning that in yesterday's new episode of The Simpsons there was an obvious reference to Up. Carl (The Simpsons' Carl, not Pixar's) and Lenny volunteer as new border patrolmen for Springfield, and, to get a better view of the border, they get on a lawn chair and attach balloons. As you can see in the above image they get up a little bit too high, and cross paths with what looks a lot like Carl Fredricksen's house (see the image below to compare).
It is odd that they'd parody something that hasn't even been released yet. But, I guess Pixar is just so big that their movies are already well-known before they get released! Watch the full episode on Hulu. Or, read my full review of Up and Partly Cloudy here!