I've been writing a lot recently about the way software is central to 3D printing. I don't just mean the (usually proprietary) software to drive the printer, or the CAD package used, but the fact that once a product is digitized, it becomes amenable to all kinds of manipulation - prior to materialization.
In one case study, a bracket was structurally optimized and ended up looking more like a tree root, weighing less yet with greater strength. In another, moving joints were inserted into a model through an automated structural analysis. In yet another, specialized biomedical modelling software was used to create detailed 'working' models of a human foot. In a consumer story, a hobbyist wrote software to allow him to print 'tunes' onto plastic disks, which could then be played on a child's Fisher-Price toy player!
The use of software in 3D printing does not stop at manipulation. Software and workflow systems can foster productive new relationships between designers and customers, and between producers and consumers. Think wikis for 3DP processes.
3DSystems has announced the availability of custom guitars on Cubify.com. The idea is that when purchased through their service, professional guitarists and enthusiasts have the ability to work directly with the designer, to create one-of-a-kind, and unique sounding, guitar for them. The customer picks a base design, and then works with the designer to customise it.
3D printing is not for what you can buy at the store, its for what you cannot buy at the store: the designer, or the design process.