You may already know about this, but if you haven't taken a look at Autodesk Dragonfly, you should!
Dragonfly is one of the many preview technologies that can be found at Autodesk Labs website. Dragonfly is using cloud technology and is a 3D environment which allows you to create simple 3D architectural floor plans. The cool thing about this, is that once you've created your design you are able to export to Revit!
The Web app will then email you a link where you can down load the resulting Revit model. It would seem Revit elements are mapped to elements drawn in Dragonfly. Considering this is a preview technology, it works very well. This certainly provides an insight into the future direction of using the cloud for architectural design.