Bespin is a project directly from Mozilla labs that proposes an open, extensible web-based framework for code editing in hopes of increasing developer productivity and promoting open standards. See the video to see what the guys at Mozilla have to say:

I think what Mozilla is doing is great. Once this project better evolves it could be extremely useful. My main caveat with Bespin is that aside from being incomplete, it lacks FTP support (which I would totally love if they…