I'm not sure how accurate this is, but it is interesting:
http://www.worldwidewords.org/qa/qa-ico1.htm
In these cases people have tried to apply logic, and it has failed them. Attempts to be logical about I could care less also fail. Taken literally, if one could care less, then one must care at least a little, which is obviously the opposite of what is meant. It is so clearly logical nonsense that to condemn it for being so (as some commentators have done) misses the point. The intent is obviously sarcastic—the speaker is really saying, “As if there was something in the world that I care less about”.
However, this doesn’t explain how it came about in the first place. Something caused the negative to vanish even while the original form of the expression was still very much in vogue and available for comparison. Stephen Pinker, in The Language Instinct, points out that the pattern of intonation in the two versions is very different.
There’s a close link between the stress pattern of I could care less and the kind that appears in certain sarcastic or self-deprecatory phrases that are associated with the Yiddish heritage and (especially) New York Jewish speech. Perhaps the best known is I should be so lucky!, in which the real sense is often “I have no hope of being so lucky”, a closely similar stress pattern with the same sarcastic inversion of meaning. There’s no evidence to suggest that I could care less came directly from Yiddish, but the similarity is suggestive. There are other American expressions that have a similar sarcastic inversion of apparent sense, such as Tell me about it!, which usually means “Don’t tell me about it, because I know all about it already”. These may come from similar sources.
.·*´¨)
.·`TCH
(..·*
010000110101001101101000011000010111001001110000010011110111001001000010011101010111001101110100
"When the debate is lost, slander becomes the tool of the loser." - Socrates
Vita contingit, Vive cum eo. (Life Happens, Live With it.)
"Life is not measured by the number of breaths we take, but by the moments that take our breath away." -- author unknown
"De omnibus dubitandum"
