Update: interestingly, according to a survey on a big M4/3 fan site, this is the most-wanted M4/3 camera ever! I guess we are many who believed it and got excited when Olympus originally shouted out (first about 4/3, later about Micro 4/3) "Coooompact quality! Compact, compact, compact!!" (OK, not in quite those words, but it was still a big selling point, and never really came through, especially before they removed the mirrors and put in the "Micro".)
Panasonic GM1 has arrived.
This is the kind of compactness I dreamed about when Micro Four Thirds was announced five years ago. The body is only the size of a high-end pocket camera! (like Sony RX100.) Funny enough it's also priced like the RX100, around $700, which I think reasonable considering the fully professional image quality. Steve Huff wrote about how he saw prints from the latest M4/3 cameras, and thought they were from full-frame cameras!
One could, and many do, question the value of such tininess in an exchangable-lens camera, because after all, you can't shoot without a lens, and the moment you put a lens on (even the very small foldable new kit lens), it's no longer pocket sized! Whereas the RX100 is, even with the nice built-in zoom lens.
But heck, it's fun. And with the kit short-zoom (24-64mm 3.5-5.6) or another of the pancake lenses it does fit in a large pocket, like in a jacket or combat trousers. And it's a great way for M4/3 shooters to carry an extra body without feeling it, and mark you that's a body without compromise in picture quality, it has the same sensor as the new flagship of Panasonic's, the GX7!
I find it interesting that they have apparently even gone to the length of reducing the outter-edge diameter of the lens mount a little bit. The kit lens has a smaller diameter than normal M4/3 lenses, so it fits perfectly, but normal lenses will stick out a little bit, with the result that the camera's bottom won't sit flat on a table! (I'm not sure about this, since from the pictures, the outter and inner edge (the latter must be fixed size of course) have the same relationship (0.73) as it has on my m4/3 cameras, which should mean it is the same size. But the reviewer had held it, and said this.)
This is another reason for the nice, but pricy (maybe $99) aluminium hand-grip, which adds a few milimeters to the bottom as well as improving the grip a lot.
Update: the reviewer confirms to me that the mount is indeed the usual M4/3 mount. It's just some large lenses may overhang, but that has always been an issue with cameras where the bottom is close to the mount. I even have an old Nikon F with a big zoom mounted, and the F's bottom is not sitting on the table.
So: no worries about compatibility.
On the left, the GM1 with the kit zoom folded in, on the right, the RX100 with the built-in zoom, also folded in.
The GM1 has a sensor which is quite bigger than the RX100's, but then the latter does really well with the one is has, and if it wasn't a bit smaller, it could not have such a nice, fast zoom lens (28-100mm, 1.8-4.9), and pack it all inside the body for travel.
Then of course the GM1 accepts all kinds of exciting and extreme lenses. Sigh, life is not easy. :-)
As the loyal reader will no doubt have picked up (!), I am a fan of compact cameras. It's more of an addiction, actually. I wish I knew why. Of course part of it is the take-everywhere aspect. Another is ease of use and transport. But a third one is some association I have between compactness and efficiency. Deep in my heart it says that if one tool does the job as well as another tool, but is half the size, then it is twice as good!
Of course, this can be tripped up by the "as good" part. A bigger camera may not be brought on trips as often, but when you do use it, it fits in your hands better probably, and due to more and better spaced buttons it will probably be faster and more certain to handle too. That's why you don't see professionals use pocket cameras on the job. (Another reason is that most customers have size firmly equalled with quality in their minds, so they think that the photographer is taking the piss if he is using a camera he can easily lift with one hand.)