Just ask Comcast.  Dave Burn at AdPulp points out that,

"While too many corporate PR and marketing departments turn a bling eye to the power of blogs, and have no clue how fast and far a story like will spread, a quick look at Icerocket turns up 157 posts and it’s still early in the story’s lifecycle."

Oh and you could talk to Dell, and have you heard about the FedEx debacle?  Looks like Comcast is getting Dell’d.