An annoying thing about the new crop of mirrorless interchangeable lens cameras is that we don't have a good name for them. Olympus and Panasonic call the cameras in their Micro-Four-Thirds (MFT) line "New Generation System Cameras", though Olympus is smart enough to de-emphasise this unwieldy term in place of the easier-to-market "PEN". Pentax opts for ILC (Interchangeable-Lens Camera) to describe the new Q, a term which doesn't distinguish this camera from SLRs. Ricoh's odd GXR design is the Interchangeable Unit Camera System. And Sony merely says "ultra-compact camera system" when they need to describe the NEX.
Individual companies don't really need to name an entire class of cameras; they can concentrate on promoting their own brand as "Q", "NEX", "PEN" or whatever. Just as well, since obviously none of their weak and formless attempts at nomenclature will do (Pentax comes closest).
Early in the gestation of this technology, some clever soul came up with the catchy acronym EVIL (Electronic Viewfinder with Interchangeable Lens). Unfortunately this label is inaccurate, since many models forsake the viewfinder entirely; users instead compose photos using the rear LCD. The acronym CSC (Compact System Camera) doesn't say much at all, unless we are in the habit of reading an awful lot into the term "system". After all, digital point'n'shoot cameras with fixed lenses can just as easily form part of a system, once you include screw-on adapters, hot-shoe flash units and other accessories.
The growing movement towards the term MILC (Mirrorless Interchangeable-Lens Camera) has at least the benefit of being accurate, but it nonetheless leaves a bad taste in my mouth -- and not just because of the dairy connection. People tend to write "MILC cameras", which is redundant.
I would have suggested ILM (Interchangeable-Lens Mirrorless) since then you can add "camera" or "system" or any other noun on the end as needs be. And it's easy to say. ("M" is better said after other consonants, since it is pronounced with a preceding vowel.)
But for some reason no-one asked me. I guess that's why I have a blog!