I recently upgraded to LR 3.0 and had an opportunity to work up an Omega Centauri Globular Cluster image. One of the upgraded features in LR 3.0 is an enhanced noise reduction tool. The new noise reduction seems to have smarter power. Meaning that is applies a stronger smoothing effect to the image while still preserving detail. Now remember some of these astronomical images contain the worst noise you can imagine. The particular screen shot here is of a 1 minute exposure at ISO 6400. I couldn't even take this photograph one year ago at those settings. So technology and software have come a long way in noise reduction. The screen is a split screen image. The image on the left is before noise reduction and the image on the right is after noise reduction has been applied.
The settings I use in this screen shot are for demonstration purposes. You can clearly see the benefit is strongest in color noise reduction. While there is still some color mottling, it is reduced greatly and the high value color noise levels are reduced dramatically. The ISO 6400 images were used to capture the extension of the globular cluster and ultimately a lower ISO image was used for the stars and background sky. But it is very encouraging to see such a noise reduction capability with ISO 6400. I tend to not apply too much luminosity reduction as the image will realize a noise reduction through stacking of multiple images. But the color noise reduction is one that really helps smooth the background sky and when stacked leads to a very clean and neutral sky background.
Once again, when it comes to utilizing a DSLR for astronomical imaging things are only getting better.
To learn more about image processing please see my "Learn Digital Photography" menu item above for customized education in Light Room or Photoshop.