I get on The Bull in my special needs bag on the run at Ironman. I haven't used it at a 70.3, but wouldn't hesitate to at the half way point of the run.
Word of warning: If you haven't tried it in training and don't drink Red Bull occaisionally to gauge your reaction, never try anything new like this on race day.
I know Red Bull isn't entirely... healthy. The taurine in it does seem to have an effect on my alertness though, and it makes me feel better during a race- even if it a placebo of something small to look forward to at the special needs bag pick up area.
If that isn't reason enough, there is always this:
http://www.bing.com/...VR28&adlt=strict
Tom Demerly
The Tri Shop.com