Microcontent is a big revolution happening in small but fast increments.  The idea is that when you shrink the average size of a "quantum" of communications, the speed and quantity of communications tends to increase.

#microcontent examples: 30sec commercial; 140 ch tweet; 160 character SMS; 100 word blog; 2 minute video on YouTube; 1 photo on Flickr; 1 sentence or picture or link on Facebook.

Twitter is an example of the principle strengthened by a enforced limitation.  Restricting the size of a message to 140 characters forces "content creators" into the discipline of writing less, which means each tweet takes less time to scan, which means people are more willing to accept large numbers of communicators and communications in a single stream, which means that communities of communicators (and consumers of communications) can grow much more quickly. 

"Twitter is going to be as impactful as “blogging” – writ smaller, cooler, faster, and more geographically relevant". @tdefren http://bit.ly/6yFmRc

A lot of questions and implications follow from that premise. 

• As Todd Defren says, it's not just about Twitter, if we took away Tiwtter now, the principle would pop up again in another form. 
• The principle applies to more than just text ... to video, audio, graphics, etc. and to many industries and content sectors.
• Thinking of content in micro-bites makes us rethink the content of content, the production and editorial  process.  How to maximize style, quality, and impact in bite-size communications, while increasing the quantity drastically?
• How much does accountability matter, and how does that affect approval and decision-making?
• Smaller and faster is great, but we're still working out how this relates to persistence and coherence in content ... where does a tweet go after it's whizzed by you, and how can conversation be turned into narrative and archive?

Arguably microcontent is just conversation writ large, because it's rewritten in digital form. But the potential impact on the way we work as a community is obviously huge.  It's already clear that shrinking average size and incremental cost  radically affects the bias of flow, from one to many vs. many to many.  Tthere's a lot still to understand about whether and how a shift towards microcontent will affect society and culture.