Web-based IDE for Ruby on Rails

I was following a couple of web-based IDEs like CodeIDE or ECCO. All of them seem to be more toys rather then actually useful tools. My understanding is that this is partially because of modest project goals and partially - limitations of technology. Let me expand why I believe it can work.
The advantage of web-based IDE is obvious – anyone, who is doing software development for a living knows how many you need to do before start coding. The idea of having web access to already configured environment where you can contribute anytime you want from any browser looks attractive. But the limitations are obvious as well. Do you think it will work in C/++ world? I really doubt that. Even with modern web-based sharing solutions like WebEx that does not sound realistic. Will it work for huge JavaEE project? Well, easy processing of large text amounts in Google Docs or Adobe Buzzword still not comfortable (yet :). We need a technology that produces output, viewable in browser and does not require megabytes of coding. It looks like Ruby on Rails sounds like an ideal choice (especially taking in mind that good RoR IDE is still missing).
Imaging being able to issue all rails commands with nice and clean UI, have a nice refactoring code editor in flash and even ability to debug RoR application. Of cause UI is the most trickiest part – it will not be possible to mimic standalone IDE, we need to do the same tweak that GMail creators did when they were re-thinking classical email client folder tree. But this certainly doable and it would minimize threshold for contribution in open source projects.
It is also very important to provide seamless integration with version control. In fact, the whole development process can be built around tasks, and task descriptions can act as a descriptions for check-ins (and thus provide meaningfull history of changes).
Also I assumes that this would broaden the audience of developers, so we need to make sure that only quality pieces of code gets to the repository. We need to have good automatic checks built-in the system, that prevents check-in of bad code (similair to FxCop in TFS) and we need to provide a possibility to manually review check-ins before integrating them into main branch (that's why git might have advantage over svn)