Yes, and you can find it in alot more places now then even just 2 years ago.
Our first trip with the kids I had to search and search for soy milk for my DD in the MK, and finally found it at the bakery on Main Street. I even asked several CM's and they looked at me like I was crazy and had no idea what soy milk even was.
But now it is offered in alot more places in all of the parks, and at the resorts.