In some of the responses that came in about How Far We've Come, a number of people expressed worries about no fast Nikon 1 primes. I know I've written an article about equivalence here, but in one of my responses to an email I replied to someone "we won't get equivalence, so we shouldn't chase it."
This is actually an important thought. The smaller the sensor, the harder it is to chase equivalence. For instance, if I'm used to shooting event work up close with a 35mm f/1.4 used wide open on my D3s (FX body), I'm not going to find anything in smaller sensor cameras that's going to match that. Why? Because I need a 23mm f/1 lens for APS and it gets worse as we go down in sensor size. The lenses I'd need are impossible to create. The only mirrorless camera currently existing that's going to get you my 35mm f/1.4 equivalent is the Leica M9.
While I welcome fast lenses on Nikon 1 and m4/3 bodies, the smaller the sensor the more I'm only using the lens speed to keep ISO down. Put a different way, when I pick up my V1--which is almost three stops different in lens equivalence for DOF than my D3s--I'm resolved to the fact that I'm going to get more depth of field. If I needed DOF isolation at a wide or normal focal length, I wouldn't have picked up my V1, simple as that.
To a slightly lesser degree, the same is true of my E-P3 (m4/3). I'm only two stops off from my D3s there, and I do have a very fast lens for it (25mm f/0.95), so I can get a normal focal length that's equivalent to...oh, only f/2 on my D3s--I still can't quite isolate the same way as I used to.
One reason why the full frame DSLRs with video have conquered Hollywood is that they are the opposite: a Canon 5DII has more DOF isolation than the big film camera we used to shoot feature films with. In other words, it gives a director of photography a new option. (Well, not perfectly true. Kubrick had a very fast lens made that he shot Barry Lyndon with that matches what's commercially available for FX cameras with video these days.)
Sometimes you just have to pick the right tool for the right job. The current crop of mirrorless cameras are not the right tool for every job, just some. Knowing which ones is important.