Cosmic Variance is another of the Technorati top ranked science blogs by scientists. Subtitled 'Random samplings from a universe of ideas' (nice), it is a group blog by five people who, coincidentally or not, all happen to be physicists and astrophysicists: Mark Trodden, Risa Wechsler, Sean Carroll, Clifford Johnson, and JoAnne Hewett. They write: 'Our day (and night) jobs notwithstanding, the blog is about whatever we find interesting — science, to be sure, but also arts, politics, culture, technology, academia, and miscellaneous trivia. We have similar outlooks on many things, widely disparate opinions about others, and will do our best to keep the discourse reasonably elevated.'
The site includes a long, although by no means complete, listing of physics/astrophysics-oriented blogs.They weigh in on the what is a planet debate here.