I downloaded the Nuke demo. I don't see any tutorials bundled with the program. There is the manual and the NUKE_Getting_Started.pdf, which helped a little bit. This is quite unfortunate. Side Effects and Autodesk bundled tutorials with their demo versions of Houdini and Maya.
As an aside, one of my main complaints is that I can't save my work with the demo version of Nuke. Many companies that make demo versions available will let the user save their projects in some sort of file format.