A new patent suggests Canon’s engineers might be working on a curved sensor design to reduce vignetting. Japanese blog Egami reports on a patent that was released on the 24th of November and describes an image sensor design with a flat central portion, where light fall-off from the lens is not much of an issue, and curved edges, where fall-off is generally more noticeable. This approach, rather than using a sensor that's totally curved, would avoid making the whole unit much thicker.
Such a sensor design could potentially be applied in mirrorless camera models where, due to short flange-back distances, vignetting is generally more of a problem than on conventional DSLRs. Software processing can correct for the effect but only to a certain degree, so it would not be a surprise that manufacturers are looking for hardware solutions.
As with all patents, it's impossible to know if the technology will ever make it into a production model but it's good to know manufacturers are looking at innovative ways of improving image quality.