
Now, when you do a search for a business (in the US), the search results display a call link next to the phone number of the business. Clicking this link brings up a field where you can enter in your own phone number. When you click the "Connect for free" button, Google will ring your phone at the number you supplied, and your (free) call will be connected. No microphone, no software needed - it uses your existing phone. Your phone number will also be saved so that you won't need to enter it again the next time.
Here's a search for pizza restaurants in Kirkland... click, click, and order!
For more info, see the announcement on the official Google blog.
