Mozilla is working on a new project called "Bespin". According to their website it is

a Mozilla Labs experiment on how to build an extensible Web code editor using HTML 5 technology.

I just signed up to check it out and it seems pretty cool. If the code for this were released to the public, developers could have this technology and build their own coding servers that would be accessible remotely. I'll post more information on this when I've tried it out a bit more.