One of my favourite physics-related blogs: Luboš Motl’s reference frame.
The content is about evenly split between very insightful discussions on the content and broader relevance of recent papers in string theory, and posts on politics and current affairs, from the perspective of a Harvard-based string theorist.
Be warned, though, that the technical discussions are fairly technical. For instance, here’s a great post on the recent Lin, Lunin and Maldacena paper, on a general solution for supergravity solutions, with a nice duality map to conformal field theory fermions.
Now if only he can get rid of his resident crackpot, Quantoken, who seems obliged to prove his ignorance with every one of his (many) comments…