I have been planning on writing on this very exciting paper, but Jean Lightner beat me to it :)
In 36 years, a group of lizards which were separated onto a different island from the rest of their species had:
In case you didn't notice the bolding, it was the development of the new organ that I found most interesting. Now, when I say "new", that just means new to them. The cecal valve is present in a number of species. However, it was not present in the population which the island was seeded with.
This gives a lot of creedence to the front-loaded "toolbox" concept of Intelligent Design. That is, species have an available set of rapidly-deployable changes which can be induced as needed. Many parts of this toolbox are shared by many related and non-related organisms.
The fact that in only 36 years all of these changes happened indicate that it was part of a built-in process.