Nokton f0.95 ?
As others stated, it is native for M4/3. I love the 25mm, the 17.5 looks intriguing, but the 25 is already very heavy and the 17.5 is even heavier and larger! It is getting great reviews.
I need to take some snaps of the lens on the camera, it looks very nice and is a pleasure to use (silky smooth action).
Couple of examples with it on a PEN E-P2, first is wide open, second is f/8
Flickr feed - http://www.flickr.com/photos/whacker/