I think company reps and even top management should keep blogs--but perhaps for a different reason than talking about their personal lives. What happens when your product starts a nose-dive in sales or customer satisfaction? Listen to your customers! Open a line of communication with them--they're people too. When Michael Dell started blogging about his computers, it gave unhappy customers a chance to vent and get their problems out there. Almost nothing is worse nowadays than an unhappy customer, who can use the internet as a tool to destroy the PR dollars spent advertising your product. Blog to talk to your customers and routinely check what works, what doesn't and what they want to see.