Eric Sloof of ntpro.nl found a very interesting PowerPoint presentation compiled in August 2010 by Iwan Rahabok who works as a Senior Systems Consultant at VMware. The presentation is divided over two Powerpoint files. One having 120 pages, the other 163 pages. It covers all the new features and functionality of vSphere 4.1 and explains them very well using pictures and diagrams.
I think this is a must read if you want to know more about the new features of vSphere 4.1!!