Well, this is a bit counterintuitive. Spotted by asobinet, Canon has patented a mechanism for a zoom lens mechanism that actually gets shorter as you increase the focal length. Yes, that’s right, the exact opposite to how zoom lenses normally work.
The patent was published on November 18th to provide zoom lenses with large apertures and small size with high optical performance. A number of lens examples are included in the patent, including a couple with ranges of approximately 28-70mm and 28-60mm with f/2.8 and f/4 maximum apertures respectively.