Wow interesting to find such an old thread that exactly describes what I saw on some night time test shots with my new (old) M8...
For what it's worth, I only tried DNG through Lightroom 3, without doing anything strange to get this, using the 50mm Nokton. The effect also showed up on the in-camera preview.
I'll try some more things tonight, like varying ISO and DNG vs JPEG and let you know