Our first Yi-Tan call was October 4, 2004 (see them all here). That means not only have we crossed the 300-call round-number threshold, but we've also been building ideas about change for six years and 13 days.

Thank you. Thanks for coming along on this journey, for jumping into the conversations, for adding links and comments on the IRC chat, for sending Pip and me innumerable emails with ideas for calls and feedback on what we've all done together.

For our 300th call, we've invited some of our past guests and will ask them each for a three-minute update on their world. Then, of course, we'll see where those conversations take us.

So with Jean Russell, Jim Benson, Michael Margolis, Doug Rushkoff, Stephan Somogyi, John D Smith (and possibly another visitor or two), let's discuss:

• What has changed in your sphere of interest? Is it better or worse?
• How are you shifting your plans and tactics as time passes?
• When do you think the next breakthroughs or milestones will happen?