Snapchat has unveiled Groups functionality today, letting you participate in threads with up to 16 friends at once. Groups can be created when sending a Snap or making a new Chat. Chats sent to a Group are deleted by default after 24 hours, while Snaps sent to a Group can be opened and replayed once by each recipient. If a Snap isn't opened, it will disappear after 24 hours, just like Chats.
When your friends are in a Group Chat, you'll see their name at the bottom. If you tap on that you instantly start a one-on-one Chat, and can easily go back to the Group with one swipe. This is apparently called Quick Chat.
Snapchat is also adding two new Creative Tools, called Scissors and Paintbrush. The former lets you cut out part of a Snap on the Preview Screen to turn it into a sticker. Paintbrush can be used on Snaps in Memories, and turns them into "artistic masterpieces", no more, no less.
Finally you'll find that Shazam is now integrated into the Snapchat apps. If you press and hold on the Snapchat camera screen while music is playing nearby, the music recognition service will start doing its thing. Once Shazam tells you what's playing, you can send your discovery as a Snap to your friends.