As TechCrunch notes, Tumblr users tend to upload, share, and re-share GIFs and other kinds of animated images, including memes, at a rapid rate, likely making Tumblr the first place where Live Photos would be widely seen and viewed.
The app was also updated with 3D Touch support. Now, users can press down on the app's icon to search the service from their home screen, activate Live Photos, and peek and pop into other users' Tumblrs by clicking on their name or avatar. While Tumblr does support Live Photos, they're only viewable within its iOS app. Other updates to the Tumblr app include the ability to send a post to any Tumblr user and messaging.
Tumblr for iOS is available in the App Store for free. [Direct Link]