This article gives many reasons why the text of the "Cmabrigde Uinervtisy" meme is deceptively easy to read, and assesses its claims: http://www.mrc-cbu.cam.ac.uk/people/matt.davis/cmabridge/

It also includes a link to a handy text jumbler written in AWK: http://www.stevesachs.com/jumbler.cgi