It seems that violence in Iraq as well as US casualties are well down since June, and that the drop in the previous few months was not just a matter of summer’s typical downturn in violence (hard to kill people in 130° weather). If the trend continues, that would be extremely good news on both counts, and might even point towards some sort of success in Iraq.
The downside: that’s if the trend continues. At the moment, violence levels are still where they were in 2005, at which point almost everyone thought that we needed rapid improvement or Iraq would be a disaster. Second, the drop in US casualties may be largely the result of changes in strategy: using air power instead of on the ground counter-insurgency. But we started using ground troops more actively because air strikes exacerbated civilian casualties and caused Iraqis to hate us more–the Kaplan article notes that civilian casualties from airstrikes this year are greater than the past two years combined.
Finally, the ultimate test of success in Iraq is political: will the various factions ever decide they don’t want to kill us and kill each other? None of these developments seem to speak to that issue. Much of our recent strategy has involved arming Sunni militias in return for their pretending to be the good guys, but nothing suggests that those militias won’t go back to their old habits if we ever cease arming them.