Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit porbelms. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
There’s a great info page on how this little thing spread not only from language to language but also on the science involved. I found the link over at the Snopes Urban Legends page. And it was a post over at It Makes a Difference to the Sheep that reminded me of this whole thing.