Some Twitter users are getting the ability to enable their accounts to receive direct, that is, private, messages from anyone, including people they don't follow. Typically, both parties must follow each other for private correspondence to be enabled, but now some will be able to open their account up.
Who, exactly? That's not totally clear. Twitter won't confirm the practice now, but sightings around the Internet show that it's happening. The company discussed this phenomenon earlier, in a July 2011 statement to The Next Web:
We have given a limited number of accounts the ability to receive DMs from accounts they don’t follow, in cases where having that capability may be beneficial (for example, enabling businesses to receive account information that users may not want to post publicly).
A more recent recipient of this account change was a marketing consultant named Jim Connolly, who tweeted a picture of his new settings:
It sounds like, at this point, Twitter isn't updating everyone's account, so don't expect a sudden reduction in person-to-person chatter in people's public feeds, or a sudden flood of Twitter spam into your DM inbox.
UPDATE: This story was updated at 1:45 p.m. ET to reflect additional information about how widespread the account changes will be. That is, it is likely not as widespread as initially thought.
— via Pocket-lint