Until now, Google+ Hangouts have been limited to people in front of a computer, but a new feature now allows you to bring in anyone with a phone -- provided their number is in the US or Canada.
To start the Hangout, you need to use the Hangouts with extras link, then invite up to two new participants by typing in their phone number. You won't get all the handy features of the video conferencing like sharing documents, and the restriction to US numbers makes it something of an oddity in Australia. That said, if you need to collaborate with colleagues stateside, it could be a useful feature.
A new extra for Hangouts with extras: make phone calls from inside a Hangout [Jarkko Oikarinen via ReadWriteWeb]