People want to do business with people. We're human, and we crave interaction with people who know us. When you build content especially for your buyer personas, you build a relationship with people before you ve even met them.
How about the opposite case? Have you recently visited a company Web site or blog and said, "Wow! These guys understand me!" Didn't it make you feel different from how those boring old sites you usually see do?
When online content seems created by some nameless, faceless corporate entity, it doesn't entice us. And we're just not interested in doing business with that company. A corporate-brochure site will never start a World Wide Rave.
That's why we keep the Smalltalk website updated on a daily basis, and why we try to keep things real on the blogs. It's also why there's a TalkBack widget right there on the left side of the blog - I'm chatting with someone now, as it happens :)