I took a few High ISO 25600 photos with the Sony Nex-5n, and I think it did a pretty good job overall. There is definitely a lot of noise, but it retains detail a lot better than I expected.
The first image is a shot of my laptop taking with the Nex-5n and the 18-55mm Kit lens at ISO 25600. I also included an ISO 3200 of the same shot for easy comparison 😉 I aslo shot the image in Raw and applied the Adobe Raw Lens profile in Lightroom 3, That helped a bit with the Chromatic Aberrations on the edges, but nothing as far as noise in concerned.
ISO 3200 for comparison
Grilled up some steaks and it was really dark over by the grill. I set the Sony Nex-5n to ISO 25600 and fired away!! I had the Nex-5n in Best quality Jpeg mode for this image, so there is a bit of in-camera noise reduction applied that results in some jpeg artifacts. It can be seen in the 100% crop, but is really not to bad at all IMO.