Here's how the one on the new 911 Turbo looks:
This happens automatically at speed, but you can also deploy it manually as we obviously are doing here!
What's new for the 2014 911 Turbo is a front spoiler that also deploys automatically or manually (ditto):
Porsche claims these devices cut a couple seconds off the car's Nurburgring Nordschleife time.
The obvious advantage of the deployable front spoiler is that when retracted, it is much less likely to get whacked when you pull into a gas station.