Olympus introduced their Four Thirds system not too long ago. Then they dropped it and ran with the Micro Four Thirds system and it looks like they are going to run pretty far with it. As far as I know there are only two companies currently using the M4/3 system; Olympus and Panasonic. Olympus is utilizing it in their smaller interchangeable lens cameras which are pretty cool if you ask me. I purchased a Olympus PEN as a M4/3 test mule recently and I love it. And then there is Panasonic with a similar line-up of small cameras. However, Panasonic took it one step further with their new AG AF-100.