In Apple’s Safari 3 (and earlier versions of the browser), you could use the up or down arrow key to move your cursor to the start or end of the text in the Google search box. This made it really easy to add new terms to something you’d already typed.
In Safari 4, however, the up and down arrow keys have been re-purposed – they now scroll through the suggested matches for your Google search terms. As it turns out, you can still jump around the Google search box using the keyboard. All you need do is add the c key to the up or down arrow key, and you’ll jump to the start or end of the text in the search box.