Hangouts is receiving a small update today, and while the changelog hasn't been updated on the Play Store just yet there are a few small differences we're noticing. First up is a new "hidden contacts" area of the settings separate from the "blocked people," giving you a way to hide folks from your contact listing but not block their messages completely. Individual chats can now have different notification sounds as well, letting you differentiate messages from calls and choose different sounds for different chat sessions.
A long-running issue with Hangouts that caused obscene background battery drain has also been resolved, according to a Google Groups thread on the issue. It may take a few days to see how it has improved, but let's hope this is the case!
Version 2.1.223 of Hangouts is available now from the Play Store link above — and as always it's taking some time to roll out to everyone.