May not work all the time, but pop into photoshop, go to the noise filter section, and click noise reduction. Then leave all the options as they are unless you want to change it, and click the box that says "remove JPEG artefacting". This is me assuming you have photoshop.
It's not jpeg artifacting, I'm pretty sure it's just noise...according to the EXIF info it was shot at ISO 3200. So to get rid of it you either need to add noise reduction in post processing (since it was shot in RAW, none will have been applied in-camera) or lower the ISO (use a faster lens and/or a tripod with a longer exposure).
Just in case it wasn't know by some visitors to this thread - JPEG artifacting is cause by the compression in the JPEG algorithm. Although it can be reduced/repaired to an extent, if you open some image and apply your photoshop skills but save back to a JPEG again be sure to save in higher JPEG quality (Photoshop level around 9/10 upwards) else you'll just introduce artifacting again as it compresses the image to save it
http://www.flickr.com/photos/39151888@N07/6945910067/in/photostream Taken yesterday on my new (Well, used) 50mm 1.8!
Went out for a play yesterday morning Castle Esplanade by steveo_mcg, on Flickr Few tourists up at this time of the morning, but they are tarmacking the esplanade... Philistines.
A big retouching project I did. I only retouch to this level once every now and again to keep my skills up. Spent 10 hours dodging and burning the skin at the pore level (5 pixel brush). Mostly wasted at web size, but will look great printed. Dani - Beauty by JazzXP, on Flickr
Carrion Crow by measter2, on Flickr I took this picture while showing my dad the zoom on the new lens. I glanced up and saw the crow, and quickly snapped a picture of it before going back to showing my dad the lens. It came out much better than I expected.
Jack Daniel's - Warms You From the Inside by ApertureV, on Flickr Trying out a new idea. Gonna have to get this shot a few more times to get it to the point where I'll really like it.
Went skiing last week, took my camera with me on the last day. This is one of the better shots I took that day. click for slightly larger..