Update: Even more stuff! Mayur Kamat posted yet another Hangouts for Chrome update, this time showing off the new link to the Hangouts phone dialer. You can see the phone icon on the top ribbon of the main interface, accessible by pressing the green quote icon. From there you can make domestic calls for free, just like on Android, or make international calls if you have available credit. If you don't see it right away, try disabling and then re-enabling the app in Chrome's extension menu.
I'll admit, I didn't switch to the fancy new and vaguely Materialish Hangouts app on my desktop computer the moment it came out. The reason was simple: I had to choose between having a little bubble on my desktop the entire time, looming over every window, or letting it sit behind those windows and potentially miss messages. The old (and still available) extension slides down the bottom of the screen as an unobtrusive handful of horizontal pixels.
But now Google has fixed this problem, tying the newer, greener version of Hangouts for Chrome into the existing notification system. If you go into the settings menu of the floating version of Hangouts and disable the "Always On Top" option, new messages or calls will appear in the familiar white alert box. Hooray for Hangouts no longer hanging its little green button right on top of the Word Count display in my writing window (150, 151, 152...). Hooray for small but incredibly useful updates.
Source: Mayur Kamat (Google+)