Niantic has detailed some of the new content heading to Pokemon GO in the near future. Two features in particular were discussed; Raid invites and Stickers.
Raid invites let you invite friends to raid battles regardless of the friend's location. In the menu, a + button will appear in both public and private lobbies. When at a raid in person, you can invite up to 5 friends to join. Your friends can see this invite in their Nearby or with push notifications. Your friends will use a pass when the battle starts.
Along with that, Stickers are on the way. You'll be able to attack Stickers to Gifts that you send to friends. At first, you'll only be able to send one of five stickers, and you can only use them once. You can get Stickers by opening gifts, and then further down the road, you'll be able to purchase them.