A few days ago Google released a new Android version, 4.4.3, which came with bug fixes and some minor UI changes. However, they also released a series of updates for their Google apps package, including the messaging app Hangouts. As you know, Hangouts is not the default SMS app in Android KitKat.The new Hangouts version is 2.1.223 (the previous one was 2.1.100). You will see that there are some significant changes in the app, but not may of them.The official changelog looks like this:
Unified SMS block list
Set custom notification tones for individual contacts
Keyboard indicator button to switch between numpad and full keyboard layouts
Hidden contacts list
Group hangouts now say "Send to group" instead of "Send Hangouts"
Contact photos pull up contact card instead of linking to G+