"First, we'll use the signal and the incredible data that we get from tweets to really tailor the experience to you," Hubbard said. "The second is this direct connection and the kinds of exclusive and limited edition products that can happen when you have that direct relationship. And the third is ... we're in a world that's moving to on-demand services—and so anything temporal, with urgency, with perishability we think will work on Twitter."
The retail partners can tweet products as part of their regular tweets, or in ads, or promoted tweets. The company says the new commerce platform won't have any impact on this year's revenue. But down the line, certainly, there seems significant potential both from the cut Twitter can take from purchases that happen on its platform and from the additional advertising retailers would buy to get more people to see the stuff they're selling. Hubbard said Twitter's ad business is based on the idea of bringing native ads, or promoted tweets, into the stream "in a way that's not disruptive and enhances the experience."
And though Twitter's early tests don't include anything like music, Hubbard said this is just the beginning: "We're starting in physical goods because that's a way for us to test the user experience. But we think that digital goods and in particular on-demand services, because of the real-time of the nature of Twitter, are a great opportunity for us. We're going to start in physical goods and you'll see us expand rather quickly."
--By CNBC's Julia Boorstin
This story has been updated to reflect the most recent number of partners Twitter is working with.