Live Preview means that you can see how something is going to look in Word, Excel, or Powerpoint before you actually commit to changing a paragraph, cell or slide. To see what a style or theme or other change looks like all you need to do in Office 2007 is float your cursor over the style or theme in question and you'll see that change temporarily reflected on the section of the document you've selected or the current active line if you haven't selected anything specifically.
In addition, Office 2007 has added a whole slew of styles and themes organized into galleries that make it simpler to format documents and presentations. Each of these styles can be viewed through Live Preview, only becoming a permanent change when you click on the style or theme rather than simply floating your cursor over it (as always, 'undo' undoes any 'permanent' change even after you've clicked on a selection).
Styles and themes can be found on the ribbon with a small box illustrating what the specific style will look like:
Here's an interactive demonstration of Live Preview as well as other features of the new Office interface including Ribbons, tabs, and the Office buttonPosted by dcoates at January 17, 2007 09:51 AM