On June 25th Secretary Vilsack initiated the USDA blog. Don't know how I missed it for so long.
Maybe it's because USDA never issued a press release on it. It sort of looks as if the impetus was the Recovery Act, not a USDA initiative on its own. Whatever the cause, I'm glad to see it. Always happy when high level program people show an interest in process and technology.
[Updated: I also see the CIO of USDA, Chris Smith, started a blog. But he has only one post and no comments, whereas Vilsack's blog has a reasonable number of posts, and a few comments.]