Anyone who participates in the "(insert name here) wore an earpiece at the debate!" theorizing is disregarding a number of very basic laws about how the human brain works. Since there were no gaps in Palin's speech – it flowed without breaks from one (talking point) to the next – she would have to be paying attention to someone speaking to her while simultaneously saying something entirely different.
Unless Sarah Palin is some sort of polymath with advanced neuro-psychological abilities to allow each brain hemisphere to operate autonomously, there would be absolutely no good reason to wire her. Do you think Sarah Palin is some sort of polymath?
Yes, handlers could speak to her while Biden was responding, but why? There are no limits to the amount of written materials they are allowed to use, hence the pages and pages of scripts that Palin read from during the debate. If she actually needed a handler over an earpiece to tell her which script to read from….well, christ, even I don't buy her being that dumb. Especially since none of the scripts had anything to do with the questions anyway. The risk of getting caught using an earpiece to say "Sarah! Say 'maverick' again!" does not seem worth it when she could simply walk on stage with notecards reading "Sarah! Say 'maverick' again!"