Google has been integrating SMS and Google Voice and now they've moved Hangouts to a floating window. The Chrome for Windows app also adds a Chrome App Launcher to the desktop and taskbar.
Not only does it launch Hangouts but also the other apps you have installed in Chrome.
Here's the list of what's new just in the latest version:
What’s new in the Hangouts Chrome app:Very interesting.
-- Native app experience. Hangouts runs in the background and notifies you of new messages and incoming calls with animated notifications. Launch Hangouts from the Start menu, have it pinned on your taskbar and switch apps using Alt+Tab.
-- Always-on-top avatars. Your friends’ avatars animate on your screen and stay on top so you never miss an important message.
-- Auto-minimizing chat windows. Chat windows auto minimize when you’re inactive to avoid cluttering your screen.
-- Message previews. Hover over any avatar to get a peek at the most recent message.
-- Drag and drop. Position the app anywhere on your screen, including multi-monitor configurations. You can also pop out important conversations and pin them to your desktop.
-- Keyboard Shortcuts. Navigate between chats quickly using your favorite Chrome shortcuts.
-- Google Voice support. Connect your Google Voice account to make calls, send and receive SMS, and access your voicemail.