Mirrorless is becoming a bit of a misnomer. Fuji is a major part of the movement with the x100, x100s, x100t etc. These have optical and electronic viewfinders but work more like rangefinder cameras of old. Their more recent models may [XPro2] or may not [XT1] have an optical viewfinder. They must have some kind of beam-splitter if not a mirror. The XT1 still has a pentaprism but yes, the mirror does not flip as in an SLR.
Fuji, Sony and Olympus are making huge steps in this smaller/lighter/quieter camera market while Nikon and Canon are moving more slowly, as you might expect.