You've actually almost proved that the famous little piece of text floating around is a hoax (well, sort of). It's not JUST a matter of keeping the first and last letters in place. For example, I stumbled for quite a while over "ispmers" and "nllmaroy". The other text could be read almost as quickly as normal text, which suggests to me that they've taken steps to facilitate the letter scrambling... grouping letters phonetically, for example.