If 4500sf counts as a mcmansion, then basically all the houses in my area is one:
http://maps.google.ca/maps?f=q&hl=en&geocode=&q=Mason,+oh&ie=UTF8&ll=39.382162,-84.303031&spn=0.008459,0.017338&t=k&z=16
For reference, the smallish looking homes on the right are around 3500sf each. The area...