Kaminsky asked more than 3 million DNS servers across the net whether they knew the addresses associated with the Sony rootkit — connected.sonymusic.com, updates.xcp-aurora.com and license.suncom2.com. He uses a "non-recursive DNS query" that allows him to peek into a server’s cache and find out if anyone else has asked that particular machine for those addresses recently.
The premissis is that all that query for these addresses are interested in downloading the patch. But later on in the article Schneier writes
In any case, Sony’s rapid fall from grace is a great example of the power of blogs; it’s been fifteen days since Mark Russinovich first posted about the rootkit. In that time the news spread like a firestorm, first through the blogs, then to the tech media, and then into the mainstream media.
In many of these blogs some of the above addresses are linked and it would not surprise me if blog-readers following these links are a significant fraction of the query sources.