While meta-moderating on use Perl, I came across an interesting journal entry which discussed whether the sixth commandment condemns killing (i.e. all taking of life) or murdering (i.e. unlawful taking of life).
I had also been taught that the meaning was closer to "murder" (though the explanation I had heard was that in KJV times, ca. 1600, the meaning of "kill" was narrower and corresponded better to what we call "murder" these days, with the general-purpose shedding-of-life verb being "slay").
Of particular interest, I felt, was one comment in that discussion where jdavidb talks about kill, murder, and translations, and points to a Google search he did as well as one of the search results, which is a document by (as far as I can tell) a Jewish scholar illuminating the situation and claiming that the misconception was far older than KJV times and was already present in Jerome's Vulgate.