Comcast’s fix for tired infrastructure and lousy customer service? Buy Plaxo.

If you’re foolish enought to be holding Comcast stock, get ready to take a hit. If you’re a Comcast broadband customer, they have a message for you: They’ve already invested enough in taking care of you and are moving on to bigger and better things. Since many Comcast customers have no alternative, we send our condolences.

Comcast, the Philadelphia-based cable giant, has finally announced that it’s buying Plaxo, a Mountain View, Calif.-based social networking & connected address book company, for an undisclosed amount of money. Plaxo, whose co-founders include Sean Parker, has raised $23 million since 2002 from VC firms including Sequoia Capital, Globespan Capital Partners and DAG Ventures.

This has been the worst-kept secret, with people speculating about the price of this acquisition. Plaxo and Comcast officials declined to comment on the price when I had a conference call with them earlier today. Even today the price range is being pegged between $100 million and $170 million. I have on authority that the price is $170 million including earnouts. This is yet another megamillion-dollar bet by the cable firm in its ongoing transformation into a web-based company with an eye on advertising dollars. (Gigaom)

Even in a non competitive environment, any company that constantly rations, raises prices and has adversarial customer service for a commodity product is doomed. An agressive competitor will eventually find a way to work around the last mile. When that happens, owning Plaxo will be irrelevant. The missed opportunity of growing and nurturing the core business will be gone. So will most of the shareholder’s equity.