As of when I just checked, there are 1,154 responses.
Besides insuring that *someone* has just won that ARC, it really highlights the difference between the number of people who read a blog, and might be moved to comment if it's fast, easy and fun, and the number of people who routinely comment on posts (around 30 to 100 for most Scalzi posts).
Blogs like the well-loved Fleen post every weekday, yet often get no comments at all. If I was Gary, I might feel like I was posting into the emptiness. It takes events like Scalzi's contest to remind me that it's worthwhile to write up what interests you even if there aren't many responses.