It has happened. Mark on Call is iPhone's "interior decorator" application that simply out bid's typical designers services at $9.99 per download. Mark Lewison is the author of What Would You Do With This Room (Amazon.ca $38.17) and owner of the company of the same name.
The application looks pretty cool for basic decorating assistance and you can take photos, scale them, and use them as textures. Yes, you can print it too. This application takes out the guess work for a lot of clients and allows the designer to focus on designing - not decorating. (If you don't know the difference, a decorator works with the existing structures and can assist with textile and colour selections - this is what most people think an interior designer is; however, an interior designer works extensivly with all aspects of the project from programming to construction documents and project managment.)
There is other decorator retail software out there for your PC/Mac by Punch, Plan 3D, and Better Homes and Gardens that range from $30 - $175 each if you're so inclined to get a little decorating done yourself and avoid hiring an interior designer.
Word of caution: This retail software DOES NOT perform load bearing analysis on your structure. DO NOT use software if you want to add or remove anything as permits are always required to ensure that you renovation or construction is done do municipal, provincial and fedral building code requirements. Alwasy hire a professional and educated interior designer or architect.