The good, the not-so-bad and the not-so-ugly: bananas at 6400, 12800 and 25600 ISO. These images were taken in dim artificial light, EXIF data should be intact so you can see for yourself. Shutter speed was around 1/6s..1/10s so there is a minimal chance of blur from camera shake, as these are hand-held - but with shake reduction used I doubt it to be honest.
JPEG's from the camera, auto-WB, settings tweaked according to personal preferences (including less sharpening). Images were cropped and resized in PSE7. No other postprocessing. I'll show the whole image (resized) and two 1:1 crops for each ISO setting.
While the K-r sensor is nothing new or groundbraking, I thought I share these as some of you are especially interested in the low light capabilities. For the camera it could be worse (we've got low light, but quite some dynamic range, histogram is well used), but still it's a challenge.
The good: ISO6400
What shall I say - would you believe this is ISO6400? WB is nice, a bit warm maybe but not unpleasant. Image is grainy, but you have to search for color noise.