How to get the hand tool back in Preview.app in 10.8?
Solution 1:
Use the move tool by pressing ⌥ Option+Space. The cursor changes to the hand that allows you to scroll the content in all directions.
Solution 2:
Here is the trick I use for large images. I select random rectangle than grab it and move selection to where I want my view span to be. Just like old hand mode. Works for me.
Solution 3:
When opening PDFs in Safari (in embedded mode), the hand tool is still available.
You could install Acrobat Reader and use this (instead of Preview) for PDF documents.