Yah, I saw a talk given on TV (on of those local channels that carrys lectures from U of W, our local school) by a Dr. on heat exaustion. It was very enlighting. One of the interesting points of the lecture was that he himself had misjudged his own condition on a hike, even though he was aware of the issues. It's sneaky.
I can't remember the exact details, but part of it covered what you want in a drink. The main thing I remember is that it sounded like
Gookinaid is a fairly optimal product. I carry a packet in my kit. I was able to find it at my local REI store (although it seems a bit hard to find locally).
-john