It is as if Twitter invented social media. Wrong.
Many of the key Twitter-isms are actually adaptations of long standing internet convention. For example, many people think that hashtags (# followed by a word or letters) was invented by Twitter users to self-organize tweets. In fact, according to Clay Shirky in his outstanding primer on social media (Here Comes Everybody), hashtags started over fifteen years ago in the IRCs (Internet Relay Channels). Users would use hashtags to create conference or chat rooms for specific conversations. Obviously an old IRCr used this on Twitter, and now you can use Twitter search to collect tweets on specific issues.
Contrary to popular belief, neither Facebook or Twitter invented status (what are you doing?). Status was created by AOL's Instant Messenger (and later Yahoo! Messenger). Your default status was online, away from my desk, busy and then you could click on it and customize. It was only a line, but Yahoo's messenger product allowed for HTML, which allowed you to include link coded words (which is better than Twitter's current text only short URL approach). People have been tweeting for over a decade via instant messengers!
Finally, people actually think that the current situation with social media and Iran protests marks a "water shed" moment. Wrong. Thousands of protestors used texting during the EDSA protests in the Philippines in 2001, leading to the president resigning. Twitter is the latest in a string of incidents where electronically organized crowds have changed the world. For more on this, read Howard Rheingold's classic book, Smart Mobs.
What does all of this mean? To find future social media innovations, look to the past. Many apps, inventions and future social media stars will adapt user breakthroughs from WWW1 (1992-1999).