And it sounds both sensible and quite unobtrusive. Kudos to Twitter for looking for ways to create revenue without wrecking a unique web experience.
From the link:
You’re probably familiar with the “Groupons” of the world—social buying sites that offer deals on everything from oil changes to spa treatments, provided a certain number of people commit to purchasing it.
To receive alerts on these deals, Twitter users will need to follow the @earlybird account. @Earlybird will tweet the deals, which will appear in your stream, just like any other tweet from users you follow.
At first, Twitter will be partnering with with select advertisers—large international brands, it says—to develop offers solely for the Twitter community. These brands will determine the price, quantity for sale and the duration of the deal. Twitter, in turn, will earn a cut of the money that the brand brings in from sales.