Haskell

import Data.Char
import Data.List
import System.Environment
zorglangue :: String -> String
zorglangue = concatMap capReverse . splitWords
w :: Char -> Bool
w x = isAlphaNum x || x == '_' 
splitWords :: String -> [String]
splitWords = groupBy (\a -> \b -> w a == w b)
capReverse :: String -> String
capReverse xs | not (all w xs) = xs 
capReverse xs = map cap $ zip (map (\x -> if isUpper x then toUpper else toLower) xs) (reverse xs)
 where cap (f, c) = f c
main :: IO()
main = getContents >>= putStrLn . unlines . map zorglangue . lines

$ echo "Zorglub, Au secours!" | ./zorglangue
Bulgroz, Ua sruoces!

J'ai passé un bon vendredi...