Update: Nikon has done something similar in the past.
Pentax filed a patent for a telephoto lens that can be disassembled into two or more pieces for easy transportation:
"Since lens barrel length is long and the whole weight of the lens barrel of super telephoto lenses is large, if it really which cannot separate such a lens barrel manufactures as a thing, carrying at the time of un-taking a photograph will become inconvenient. Then, after dividing a lens barrel with such a long overall length into two or more removable cylinder members, The moving mechanism for moving a moving lens group (focus lens group) and a moving lens group to the cylinder member by the side of front, If the focus ring for operating this moving mechanism is provided and the cylinder member on the backside is used as what is called an extension tube (cylinder member which does not build in a taking lens), carrying of the lens barrel at the time of un-taking a photograph will become easy.
Such a division type lens barrel of structure can perform looking-far photography by manual focus by carrying out manual operation of the focus ring provided in the cylinder member by the side of front, observing a photographic subject. If the signal transmission medium which transmits a signal to the cylinder member on the backside between the cylinder members by the side of a camera body and front is established, AF operation (auto-focusing) and diaphragm adjustment operation by the camera body side will be attained."
Via Egami
