This project is considered inactive.
The Mozilla Skywriter project, formerly known as Bespin, has been merged into another project. If you're looking for a customizable editor that you can embed in your own projects, take a look at Ace. If you're looking to do your coding in the cloud, take a look at Cloud9 IDE which builds on Ace (and Ace includes code from the Bespin/Skywriter project).
See the announcement blog post for information about the transition from Skywriter to Ace.