Google's Gmail isn't just a mailbox -- it now doubles as a phone. Users of Google's Web e-mail service can now call any phone in the U.S. or Canada for free (and make international calls for almost free) from within their browser.
Google announced this feature in a blog post a few minutes ago. It seems to be built off the voice and video chat feature Google added two years ago, as it requires installing a new version of its chat plug-in, available for Windows XP or newer, Mac OS X 10.4 or newer and some versions of Linux.
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