At the ESRI User Conference Bill Miller, Director GeoDesign Services at ESRI, previewed  a web-based app to support the geodesign workflow.  The app is aimed at the planner and is designed to support land use planning, coastal land use planning, disaster response, and similar types of workflows.

What is revolutionary about this app is that it is not a traditional GIS product designed for GIS professionals with years of experience.  From what I saw it was intuitive, fast, and easy to use with no or little training.  Users can setup their own projects, use Esri or their own data, create plans(scenarios), assess and evaluate them, compare scenarios (ala Urban Observatory),
invite people to collaborate synchronously or asynchronously, and share their work with others, all with no or minimal training.  It uses HTML5 and Javascript and so can run in a browser without a plugin on any device. 

Some of the things that Bill demonstrated included

• create/open a project
• invite other people to join
• draw points, lines, polygons freehand
• use symbol palette (land use types)
• set transparency
• choose/change basemap
• show slope, aspect, and elevation
• open scenario/create scenario
• copy polygons from one scenario to another
• open a dashboard
• customize the dashboard
• choose layers and weights for a suitability model
•  run a model, for example, to calculate suitability for open space conservation, or industrial, residential, commercial land use
• compare result maps generated from different scenarios side by side
• create reports by harvesting dashboards, comparisons, and metrics
• collaborate so that two or more users see edits in real-time in their browers on different machines
• synchronize map extents so two or more both users see the same work area

Currently it only supports 2D, but it appears to be the intention that 3D would be supported in the future.