I just was there yesterday (7/21) and, like others have noted, the printed doc they gave us did not include Splash as one of the attractions. (It only had 4 "Donalds" -- Thunder Mountain, Pooh, Peter Pan, Space Mountain.)
I hadn't seen this thread in advance and this was quite a surprise. I asked the cast member at will call about it, and he seemed as surprised as we were. He just said, "I guess not." This was a real bummer, because we'd done a whole touring plan in advance that sort of depended on using GAD on splash, but instead I served as the fast pass runner first thing in the morning to get the fast passes at Splash. After getting them, I tried the GAD fast pass card on Splash and it did work despite not being on the list. So, I did a morning run for nothing, but it turned out fine. Maybe the computers haven't caught up with the change yet. Not sure. Sounds from this thread like it's hit or miss.
The one thing I didn't want to chance, though, was waiting to try to get our GAD fastpasses at Splash after fastpass distribution was closed. I was concerned that since its' not on the list they might not have kept a machine open. So, I got all our GAD fastpasses for Splash in advance.