In 2010, Twitter hosted its first developer conference, dubbed . It appeared to be following the model of companies like Facebook and Google, except Twitter didn't repeat the event; it hasn't held another major conference for developers since.

"Spirits of developers were high" at Chirp and "the smell of one common thing, building the Twitter ecosystem, was in the air," Richard Grant-Gailums, CEO of Veritweet, said via email. His company verifies the identify of all its users, so no one tweets anonymously.

When Twitter TweetDeck in the middle of last year, its attitude toward third-party developers cooled, Grant-Gailums said.

Jeremiah Owyang, an analyst at Altimeter Group, said it's not unusual for social networks that clamp down on their APIs' (application programming interfaces) use to see some backlash. "The initial approach is 'let a thousand flowers bloom,'" he said. "But then once they start blooming, the networks realize that they're missing out on monetization opportunities."

In Twitter's case, it seems the company is eyeing advertising opportunities through its expanded tweets. If the feature takes off, users "should expect that standardized advertising units will be deployed across these cards," Owyang said.