Last Updated Nov 7, 2010 11:51 PM EST
When you're ready to practice, click the Slide Show tab and then click Rehearse Timings. The deck will start up in presentation mode. Practice your speech, changing slides as needed. When you're done, you'll see this message:
Now, when you view your slides in Slide Shorter mode, you can see how long you stayed on each slide. That's handy: If you need to shorten your presentation, you can see which ones you spent too much time on, and fine-tune your timing.
And when you run your presentation, it will even auto-advance the slides according to that timing. Don't want the slices to auto-advance? Clear the checkbox that says Use Timings. [via How-To Geek]