Medium format digital cameras are out of reach for most, but Pentax has been providing ones on the "affordable" side (under $10k), for a few years now. Their new guy, the 645Z, packs a brand new, friggin large, 51 megapixel CMOS sensor.
It's not a micro four thirds, but Pentax has lifted the lid on the 645D medium format camera, which will be available this May for close to $10,000. Why so expensive, you ask? There's that 40MP Kodak sensor for starters.