To answer some of the many questions I am getting daily...
Yes, there will be a Hidden Power book for Elements 4.
Yes, the book will cover all of the power tools that were created for Elements 3, including Curves and Color Balance.
The book will take a few months (February?) before it is available...
http://aps8.com/hppe4.html
The tools will be available separately from my website when the set is complete (January?):
http://hiddenelements.com
If you have other questions, please ask them here.