Here's a quick shortcut to let you activate the new Google Instant Preview via your keyboard.
Google Instant search is fast, but we like making it faster with keyboard shortcuts. Activating Instant Preview via the keyboard is dead simple. You press the down arrow to access your search results and the right arrow to see the preview. You can just keep pressing the down arrow to continue moving through the results and displaying previews as you go along.
@Steve Rubel [Twitter]