You have been able to create 3D models on your desktop with non-CAD tools such as SketchUp for awhile. Lately, the trend has users creating 3D in their browsers. The recent open-source Google O3D program is a good example. An “interiors” demonstration shows fairly complex 3D architectural models being displayed in a browser. The application reminds me of Autodesk's Project DragonFly except it lacks the 2D layout tools. Project DragonFly actually uses a Flash rendering engine (not the Google technology). I found the program's use to be smooth and responsive and was able to quickly build what I call my “small house” model in my browser.
With all this going on, it seems likely that programs such as SketchUp might eventually get delivered directly through the browser rather than as a desktop application. Maybe CAD will follow?