Andrew Stanton, one of Pixar’s Directors:
We just happened to be, sadly, the first production up that was Disney that wanted to give [a dedication]. And I personally wanted to. I talked to John [Lassater] about it because I didn’t want to steal any thunder from Pixar’s dedication because that’s really the real family member for Steve. But it felt right just cause I didn’t want too much time to pass without giving him some sort of permanent acknowledgement. And I talked to his wife. [Source]
Steve Jobs bought Pixar from George Lucas, who created the company to help develop computer generated effects for movies. Although Jobs originally thought the company could use their graphics development abilities for business, he soon realized that it could do more than that, after being shown a short cartoon made only with computers. Their first commercial success, Toy Story, revolutionized the way animated movies are made, and the rest is history. A well deserved homage.