You can now shoot with the front-facing camera. When creating a post, tap the button in the bottom left corner to try the front-facing camera. You can switch back and forth between the regular and front-facing camera as many times as you want.
Vine now supports mentions, so you can tag people in your post. Users who are mentioned will receive a notification in Activity. To mention a user, type @username and select the name among the suggestions you’ll see. See the screenshot below for an example — when I type @chris, I see suggestions for Chris Fry, Chris Hardwick and Christofer Drew. When I select Chris Hardwick, his Vine profile will automatically link in my post’s caption.