Whether people believe it or not, Google is secretly becoming the default for a lot of things. It looks like it's going to be the same for video conferencing. While they're a lot of video conferencing software out there to use (Skype, Oovoo, Tango, etc...), it seems like Google Hangouts are starting to become more popular as time goes on.
When Google introduced Google Hangouts as part of Google +, they're goal was to provide new ways of sharing across Google. It wanted you to show the world who you are and what you're into while connecting to others who share similar interests. Google Hangouts provides free video chat, where you can chat to ten people at one time.
While Google + is still growing at a steady pace, it seems Google Hangouts is starting to become more of a main feature to sign up a little quicker. More users are using Hangouts for video chatting and I believe that it's going to continue to grow. Google Hangouts originally was available to the users with a webcam, or having an Android device running Ice Cream Sandwich (ICS) or higher. It was limited to previous version Android devices and iOS users until now.
With the updates on Google +, you now have the ability to start and participate a hangout in most devices. This is a huge step because you can now video chat with virtually anyone that has an iOS device or an Android device. While Skype and Oovoo does provide similar type of video conferencing, the integration with Google +, and YouTube make Hangouts the default choice for video conferencing. It's also Web-based to make it a "+" (no pun intended) to use.