In general, it's not a new idea; software companies have long sold expensive authoring software for their free viewer programs. Shockwave, Flash, QuickTime, Rea

In general, it's not a new idea; software companies have long sold expensive authoring software for their free viewer programs. Shockwave, Flash, QuickTime, RealPlayer, and Viewpoint have all tried to use this business model for browser plug-ins. However, it's the most direct attempt I've seen to apply the business model to an already open standard.