Wall St. J. opines this is partly due to the bad economy, which prompts couples to avoid divorce. Maybe, but I'm dubious for two reasons. First, it is a relatively small drop in the divorce rate, consistent with previous trends. Only if there were a deviation from the trend would we speculate that the instant economic downturn is in any way influencing behavior.
Rather, this looks like a rational continuation of logical trends that have developed since the national introduction of no-fault divorce (yes, NY technically still does not have no fault divorce, but it does in practice). Prior to 1973 (when CA adopted no fault divorce), a lot of people were stuck in unhappy marriages. Enter no fault divorce, along with numerous other changes that impact social patterns (entry of women into workforce, rise of two-income families, reduction in birthrate/overall ability to control fertility, removal of stigma associated with pre-marital sex, greater involvement of men in childrearing, introduction of domestic partnership laws eliminating many economic reasons for marriage). Unsurprisingly, marriage changes and a new pattern of stability emerges. On average, people are marrying later, after longer periods of association and engagement, and frequently after living together for extended periods. All are factors that one would expect to enhance stability in marriages overall.
It will be interesting in a few years to see whether broader adoption of same sex marriage alters the statistics.