“It needs to be water. It’s instantly useful. It’s simple. I don’t have to re-learn how to use water,” he told the audience. “It’s always present.”

To that end, Costolo and the rest of the Twitter team are meeting with carriers, original equipment manufacturers (OEMs) and platforms, to ensure that the service is integrated within the consumer experience on a great number of devices.

Forty percent of all Tweets today are created from mobile platforms, Costolo said, adding that fifty percent of all active Twitter users are active on more than one platform.

Costolo stressed Twitter’s intention of providing the user experience itself on these platforms, rather than ceding to other players.  (One of those, Tweetdeck, was recently acquired by UberMedia for $30 million, according to reports.) Part of its effort to become ubiquitous will require its apps and site being translated to other languages. Costolo said it would be crowdsourcing translations to Russian, Indonesian and Turkish, and would take on translating Twitter to Portuguese itself.

Regarding its revenue-generating potential, Costolo said businesses were already finding Twitter valuable for customer service and branding initiatives. “All we had to do is provide them with an ability to enhance that communication, and that’s what we’ve done,” he said, without specifically mentioning the Promoted Tweets or Promoted Trends products.

Costolo emphasized the impact Twitter has already had on one business — television — saying that the service, and the real-time social interaction it enables, was negating somewhat the impact of the DVR and time-shifting. “Because of this social context,” he said, “people are starting to watch all sorts of television programs in real time again.”

“When [the television show Glee] is on in the U.S., the moment the show starts, the Tweets per minute about that show go up 30 times,” Costolo said, adding that Tweets stay at the same level until the show concludes.

Costolo downplayed Twitter’s significance in recent world events in Tunisia and Egypt, crediting instead the people that found a way to use the technologies at their disposal. If Twitter were like the water fish swim in, Costolo said, borrowing a story from the late author David Foster Wallace, they’d cease to notice its existence. “[Twitter will] be like the water,” he said, “and all we’ll see is each other.”