For those that like to use the Hangouts Chrome app will be happy to know that a nice update came to it today. Now it includes a phone tab to allow calling from the desktop. You can start an SMS thread directly from the app if you have Google Voice. And now it has proper desktop notifications.
It seems as though the Hangouts team is constantly working to provide a better overall experience with their messaging platform, which was not the case with Google Voice or Google Talk. It is nice to see constant development.
To download the Hangouts Chrome app, head to the Chrome Web Store