I saw an article on MSN this morning,
http://www.msnbc.msn.com/id/29019618
This part is what makes me think it's all about marketing their other Disney films, even though they deny it.
Here is the quote: "Disney has woven a few bars from some of its hit soundtracks into the classic "Small World" melody and added a new America section that includes a nod to Los Angeles' famous Hollywood Bowl, a quaint farm scene and "Toy Story" characters."
I think I'd rather just hear it's a Small World than it be interwoven with Disney tunes

My mother will be sad.