There are a lot of ways to run a blog promoting your publishing company. Dark Horse uses its blog primarily to remind readers of new product. DC breaks news about its comics and runs interviews with its creators. Top Shelf and First Second talk about their own product, but also make time to discuss books they're enjoying from other publishers.
One of my favorite publisher's blogs right now is Hermes Press' relatively new one. Since they publish a lot of reprints of classic. licensed material, they not only keep readers updated on their publishing schedule, but also link to news about what others are doing with those same licenses. For example, Hermes is reprinting old Dark Shadows comics, so they're also following production on the Tim Burton Dark Shadows movie. They reprint Buck Rogers strips, so here's some news about a Buck Rogers screening in New York. They reprint Roy Rogers, so here are some links to other bloggers who are talking about Roy. It's a fun blog that doesn't just promote product; it engages in the larger conversation about the things it's interested in. Some of the other blogs are doing that too (First Second and Top Shelf in particular), but Hermes is going all out.
What makes a perfect publisher's blog in your opinion?