The Economist.com does Robert Scoble, and asks if he as “celebrity blogger on Microsoft’s payroll, herald the death of traditional public relations?”. (Congradulations!)
My own answer would be no, but it does challenge the tradition value that “traditional public relations” bring to the table. Corporate blogging is also useful for things smaller than a News Article or PR posting would consider like : Internal milestones, hiring events below the C-level. Call it Nano People Relations. (PR without the spelling?)