The Unicode people don’t sit around and invent characters – nor do they systematically determine the complete list of characters that should be in the standard.
Instead, they consider proposals from people who want their already-in-use character sets to included in the standard. So if someone proposes SINGING OCTOPUS, DANCING OCTOPUS, and SINGING SQUID, but not DANCING SQUID, well, DANCING SQUID won’t be in Unicode. There are lots of gaps like this.
Interesting. I'm also on iOS 6 and both show up for me. I wonder why.
Edit: in safari, the symbol shows correctly in the window header, but not the page itself. In news:yc, a hacker news app, the symbol shows up fine. It also shows up in the WebView in news:yc.
I haven't looked at the Supplementary Multilingual Plane: Miscellaneous Symbols And Pictographs [1F300...1F5FF] in a while. My favorite characters are 👹 (Japanese Ogre)👺(Japanese Goblin)👻(Ghost) and 👽(Extra Terrestrial).
The symbol 💣 (Bomb, 1F4A3) is useful for reviewing movies using Leonard Maltin's notation.
My IE10 octopus is missing 3 arms and a mouth, resulting in something that looks more like a 3-legged grey alien trying to surrender than an octopus who is smiling.
Instead, they consider proposals from people who want their already-in-use character sets to included in the standard. So if someone proposes SINGING OCTOPUS, DANCING OCTOPUS, and SINGING SQUID, but not DANCING SQUID, well, DANCING SQUID won’t be in Unicode. There are lots of gaps like this.