On the 22nd of April Brian Tinsman and Erik Lauer, the lead designers of the latest Magic the Gathering expansion held a dev chat about said expansion. In general it was terrible, not because of Erik or Brian, but because the questions were horrid.
The next day, @mtgaaron (Aaron Forsythe - Director of R&D for Magic) did his own Q&A, he did it on twitter. It was shorter in duration but significantly better than the dev chat, the reason for this is that Aaron could filter out the cruft questions, and answer the questions he found he could answer.
Today @PeteCarroll (Pete Carroll - Head Coach of the Seattle Seahawks) did the same thing. He tweeted who's got questions? gonna answer some for the next few minutes... fire away! and proceeded to answer random questions sent his way.
What is my point in this? Well, twitter has allowed people that generally don't get to communicate with random public access to the masses. Before twitter how could a head coach of a pro sports team ever answer fan questions in such a manner with so little effort? When could a person like Aaron Forsythe be able to answer concrete and relevant answers to MTG players?
So that is, my friends, one example I believe in how twitter is changing