Eastman Kodak and a young company named Foveon have each announced image acquisition chips and prototype digital cameras with resolution of 4096x4096 on a 22mm x 22mm chip, i.e. about 16 million pixels per square inch at the imaging surface. This is approximately the resolution of conventional photographic film. (A brief informative article comparing film resolution to digital image resolution is at http://www.luminous-landscape.com/pixels_vs_film.htm)
Foveon's founder is Carver Mead, who is more or less the inventor of chips for image acquisition.
Foveon's home page is http://www.foveon.net/
Kodak's 4k x 4k sensor is described at http://www.kodak.com/country/US/en/digital/ccd/kaf16800.shtml it's on a slightly bigger surface and is likely more expensive to produce (different technology) than Foveon's.
Both devices are monochrome, so it might be another year before we see color of this resolution, but both companies behave, and speak, as though they do not expect silver halide technology to be around much longer for capturing images.
--Bob
[Apologies to tdwg mailing list if this is far off topic. I know that many of you are interested in the subject]