It is now being used to create not just small-scale plastic models, but also functional objects like prosthetic limbs and (soon) entire concrete houses!
Although the printers are costly hobbyists can purchase starter kits for around a thousand dollars.
More affordable is sending your SketchUp files away for printing. SketchUp offers methods of making 3D printing work for you at home. Check out this link from the SketchUp blog.
Also be sure to try your hand at the 3D printed lamp Design Challenge from SketchUp and i.materialise. Contest entry deadline is October 25, 2010!
EDIT: Check out this article from new York Times about New York-based 3D printer Shapeways. "[Customers] concoct their own creations from scratch with software like Google SketchUp."