Yes, you are reading correctly. That is a 42-inch Nexus S pictured above. It is located in a Best Buy in San Carlos, California to bring attention to the brand new Nexus S, only available in Best Buy stores. Unlike other previous large demo phones this is actually a working phone powered by a smaller Nexus S, which is why the screen is a little less than perfect with the touch abilities. It goes without saying that though a great focal point and conversation piece, it is pretty much just for show, though I wouldn't mind having one for bragging rights at least.
Google stated that this is a test to see how the device fares in this store. If it proves successful they will roll them out to other Best Buys, maybe even one near you. Thanks to Tech Crunch for this video of the largest Android phone ever in action.