We've been 3 times since 2002 and never had a problem with snack or drinks.
I don't think any of the disney parks care what you bring in unless it's something dangerous to the park, it's employees, and the guests.
Our first trip was in January 2002 and they just started bag checking at make-shift tables. When we went back last April it seemed the parks had dedicated areas to check your bags.
BTW, we leave this Friday (April 29) for a week in Orlando-w00t!!!!
We will take water (so we can refill the bottle), fruit snacks, crackers, and probably some sort of breakfast bars.