A few weeks ago, Tech Crunch’s Michael Arrington blogged about a phone call he received from a Comcast executive, just 20 minutes after “tearing into [the company] on Twitter” over his extended Internet outage.

Probably not a coincidence, right?

And as it turns out, the cable company/Internet service provider is routinely following and responding to complaints and questions posted on Twitter through its @ComcastCares account — and that’s true for customers whose names aren’t Michael Arrington (otherwise known as the No. 2 blogger on the Technorati Top 100), too.

Shortly after hearing the Arrington story, I decided to throw Comcast some feedback of my own on Twitter — partly out of frustration with a billing issue and partly out of curiosity. Frank from @ComcastCares responded within 15 minutes, kicking off this full exchange:

Twitter exchange between Comcast and Bryan Person

Last weekend, I took Frank up on his offer and e-mailed him more details about my account and billing dates. Again, to my pleasant surprise, I had a reply within a few minutes — this time via his BlackBerry.

We made some progress on the invoicing front — Frank is going to recommend that Comcast put the actual late-payment date on future invoices — but probably more importantly, I came away impressed that my cable provider really does care about its customers.

And for a company that doesn’t exactly have the best reputation on the customer-service front, Comcast could certainly do plenty worse than mending some fences through a site like Twitter. I know I’ll be sharing this story in future presentations that I give.

It isn’t just Comcast

Comcast isn’t alone among businesses that are smartly monitoring and responding to mentions on Twitter.

Disqus is, too. And Southwest. And Zappos.

What about your company?