Yesterday Instagram added tagging to their service, so you can identify friends who are in your photos. Facebook and even Google+ have had this for a while, and it's fine. What I really want, however, is in-network sharing. The ability to share great Instagrams on Instagram.
On Twitter, if a friend tweets something amazing, I can re-tweet on Twitter, and the people who follow me can discover it. On Google+, if a friend posts something amazing, I can share it on G+, and the people who follow me can likewise discover it. Many other social services have similar features. Friends retweeting or sharing within the network is how we all find new and interesting people to add within those networks. It's the easiest, simplest way to grow.
On Instagram, I can Like amazing photos, but I can't share them with my friends on Instagram. If @safesolvent hits "The Stance" on top of the most spectacular cliff imaginable, or @davidlundbladphotography captures the perfect fashion candid, I have no ability to let anyone else on Instagram experience it with me -- I have to use the built-in feature to share to Facebook or Twitter, or manually share to G+ or other services.
In-network sharing is such a common social feature that Instagram certainly must have considered it, and must have gotten the request for it multiple times. Their vision for the service may not align with sharing, or they may not yet be ready to introduce it the way they want to.
Still, it's something I'd love to see, and sooner rather than later. There's so much amazing work on Instagram, it's a shame it can't be shared on Instagram. Let me know what you think, either in the comments below or on Instagram