From a WSJ interview between Walt Mossberg and Twitter CEO Evan Williams and co-founder Biz Stone. Mossberg had asked Williams about whether commercial accounts on Twitter would be a good idea.

MR. WILLIAMS: The theory is this: There is a lot of commercial usage on Twitter today. There are lots of big brands on Twitter, using it as a marketing, communications and customer-support vehicle. There are small businesses using it to just connect with their customers and build relationships.
It seems like we can maybe offer them things to do that more powerfully and more efficiently, and things that don’t interfere with and actually benefit consumer users.
MR. MOSSBERG: Give me one or two examples.
MR. WILLIAMS: People are fans of Dunkin’ Donuts. They have a relationship with the company, they go there every day. Dunkin’ Donuts is using Twitter to communicate with those people. There are people who are finding value in that. There’s thousands of people, I don’t know how many thousands now, following Dunkin’ Donuts.
So if that’s the case, if you are a new user to Twitter and you stumble across Dunkin’ Donuts, the first thing you want to know, is this really Dunkin’ Donuts? If you’re Dunkin’ Donuts and you have a brand to protect, you want to look legit, and you want to make sure no one else is trying to interfere with your brand.
MR. MOSSBERG:Like a Starbucks pretending to be Dunkin’ Donuts. So the first thing is you have some way for Dunkin’ Donuts to establish it’s really them?
MR. WILLIAMS: A service we could offer as the middleman.
MR. MOSSBERG: Some sort of authentication.
MR. WILLIAMS: Say yes, this is Dunkin’ Donuts. We check them out. It’s something that will take us manual effort to do and a little time, so we’ll probably want to charge money for that.

Now, to be fair, this is a hypothetical conversation about a hypothetical service so we’re just talking here. Having said that, my immediate reaction was kneejerk – Twitter proposes to charge Dunkin’ Donuts so that it’s not confused with the x number of Twitter users who are infringing Dunkin’ Donuts? What nerve! How about instead, Twitter merely does not commit contributory infringement by not allowing x number of users to infringe Dunkin’ Donuts.
But there’s another way of looking at it. There can be the universal not-necessarily commercial, unregulated, unzoned Twitterverse, where the Twitter name EXAMPLE does not imply that it is the sole source of EXAMPLE goods and services (just as the gmail address EXAMPLE@GMAIL.COM has little impied authenticity; and inside the universal unregulated Twitterverse is the commercial regulated zoned Twitterverse, where the Twitter name EXAMPLE does function as a trademark. And it seems plausible to charge for maintaining that commercial zone.