It does seem pretty useful for generating source data. If it's good enough, you can scan an item, tidy up the data a bit, then print it put on your RepRap. The system then becomes a 3-d copier.
So, is it up to the task?
You need a webcam, a laser line (either a laser level or a laser pointer), and the software.
I used an old webcam (640x480), and a red laser pointer (5mW) from ThinkGeek - but they're pretty readily available.
The software comes with a few different templates - basically a dot pattern you print out. You then attach the pattern to two sides of a 90 degree corner - like the inside of a box, or two card sheets at right-angles.
You then point the webcam at the box, and 'paint' it with the laser line. The webcam can see the shadow of the line on the object and the background, and can work out the 3-d profile of the object.
To turn a laser pointer into a line, you need to bounce it off a curved surface (I made a line with a shiny metal knife handle), or shine through a glass cylinder. Wandering around Bath, I care across a shop selling christmas decorations - and they had a nice glass raindrop - shape:
Shining the laser through the glass cylinder produces a nice line:
I snapped off a short section of the glass and polymorphed it to the front of the laser. I've now got a simple laser line.
Initial playing with the software gives an idea of the result - I think it needs a bit of careful configuration to get the best scans out of it, but the potential is definitely there.