Free Calls to US & Canada with Google Voice

When I was checking my mails in Gmail, I saw this little green phone icon where you can find the list of your chat contacts.  This phone icon is labeled as "Call Phone".  Out of curiosity, I clicked this icon.  A dial pad popped out and a message prompting you to "download the voice plug-in".

It turns out this is a Google's new feature that allows you to make FREE calls to US and Canada.
You can also make international calls to other countries with minimal charge.

I haven't tried this yet, but if this really works and is FREE, then what are you waiting for?

More information on Google Voice here:

URL:  http://www.google.com/chat/voice/