DPReview has a vote going on to find out what people think the new mirrorless format should be called. They have a list of six options, but none really make sense to me. Just in case it ever takes off, I've got to put down what I would name the genre of cameras: High Fidelity Compact (HFC) or HFDC (high fidelity digital camera).
The issues with all the names they have, in my opinion, is that they don't distinguish from Point and Shoots with tiny sensors (which have never used a mirror) or by including the word 'system' they try to only include cameras with interchangeable lenses. But I think most would agree that the Fuji X100, Leica X1, Ricoh innovatively odd lens module system, Sigma's DP1/2 and so on are all contenders for dollars when it comes down to cameras like the micro-four thirds and Nex offerings. To me, it all comes down to the sensor size. Yet the mFT sensor is so close to an APS-C sensor it would be a mistake to rule out bigger sensors (surely the Leica X1 or Sony Nex are pysically smaller than the GH2 with bigger sensors). Mirrorless really just defines the viewfinder technology - so what about the new Fuji camera with a fixed mirror in the viewfinder.
Anyways, to me the 'format' encompasses too many different technologies to to try to build a name around any of those features - or you just exclude new developments from the field. I think it is all about getting higher images quality out of a small form factor camera. At the same time, the physical sensor size is kind of irrelevant - if we can get super high quality out of a sensor smaller than MFT in 5 years, will we care about that technicality, or just that it is high quality and fits in a pocket?