The story about this new Da Vinci Last Supper theory drives a lot of interest. As reported Slavisa Pesci, an IT guy says that he found new figures in Da Vinci's Last Supper artwork by superimposing a reverse image of it.
Other person claims to have made these Da Vinci discovers earlier - more theories
Australian News.com has a nice slide show that shows the effect when superimposing a mirrored version. There is a shadowy image on the left that I see with lots of imagination. The figure holding the baby I do not really see.
See the Last Supper Theory photos for yourself on News.com.au. Photo above by AP.
About.com (Thanks Dwayne) has some indepth look at Da Vinci theories.