It currently has about 260,000 shares, but that's mostly people sharing from Daily Kos, and as many of you know, viral stories also percolate within the social networks themselves (like people retweeting tweets).
Now there are other diaries that have higher readership, but most of those gathered that audience over months or even years. No other diary has had this much reach this quickly.
Yesterday, about a 15-20 percent of the people visiting Daily Kos were reading that story. Today, it's about 25 percent -- so it's growing despite now being two days old. In fact, this story (in addition to heavy traffic from Occupy Wall Street Coverage) has now helped Daily Kos to record traffic: