Can a wiki be a discussion board?
Aaron Swartz writes how the open wiki for Echo/Atom turned out, when it was used for conflict resolution. The bottom line, use loosely connected task specific tools.
Longhorn Aero Screenshots:
Winsupersite has the latest screenshots of the ultra secret “Aero” release of Longhorn. WinXP got the navigation right with the task pane, Longhorn is trying to get the task-oriented pages right. You can also see a dashboard which keeps track of your latest alerts similar to centrals’ console in one of the images.
One Hundred Interesting Math Calculations:
Brad DeLong has a public wiki with interesting math calculations. How many years will it take for the total mass of all the humans to be equal to the mass of the earth? Ans=1750 
Getting ready for Internet 2.0?
Founder Emeritus at Macromedia, Jeremy Allaire shows 10 trends that point to Internet 2.0. Also, John Robb lists some ways to build Web 2.0 apps. He also describes what web 2.0 is here.