In the Wikipedia entry for Uruk-Hai, it states that some Uruk-Hai had an elf rune, equivalent to the letter "S", painted on them. It then states:
It was clear the "S" stood for Saruman, considering Sauron's general desire not to have his name written or spoken. Wikipedia Source
Although there is no source provided for that quote. Can anyone quote something in the books (or the film, for that matter) about Sauron not liking his name being written or spoken? I haven't heard of that, and although I have my own theories for why he might prefer that, I'd like to see it straight from the books!