E-dreamz, an interactive firm in Charlotte and where I interned at during college, recently published a blog post discussing the "similarities between Twitter and Inbound Linking strategies." Simply put, Twitter has mutated into another way for businesses to hock their wares, while the real draw of the service is from nothing of the sort.
For me, Twitter is the asides between the conversation. Quick commentary and reflection, no matter how mundane, is what has made Twitter successful socially. Twitter is not a notification service for your latest blog post—that's RSS.
Setting up a Twitter account doesn't automatically create the appearance that a business is "connected" to its customers either. As Merlin Mann commented in a recent podcast from SXSW (I'm paraphrasing): setting up an account on Twitter does not make you Zappos—putting resources behind serving your customers makes you Zappos. It takes time and effort, like everything else.