Tools and culture for No-Email company?

GitHub and TreeHouse have talked here about running companies that largely eschew email.

http://zachholman.com/posts/github-communication/ http://ryancarson.com/post/63593803482/how-to-communicate-in-a-nomanager-company

Both of these use internally built tools.

http://abcnews.go.com/blogs/business/2011/11/tech-company-implements-employee-zero-email-policy/

These guys use a wiki and chat.

Has anyone here successfully gotten a company to minimize email? Can you talk about the tools and cultural changes and activities that helped you?