Update: check out our special Mirrorless on the Job review about the E-M1!
Our OM-D E-M1 hands-on coverage:
The new Olympus OM-D E-M1 represents a fusion of two distinct systems: Four Thirds and Micro Four Thirds. Olympus did develop a new Four Thirds DSLR, the E-7, but then decided to drop the project when they realised they could incorporate the best parts of both systems into one single camera. The body remains compact but includes all the features we professionals need, and works seemlessly with all Olympus Zuiko and M.Zuiko lenses.