All of the OurMine messages posted to Dorsey's account (which, as of 3:25AM or so appears to have been scrubbed of the hacker's tweets), came through from Vine. It's possible Dorsey had an old/shared password on his Vine account or somehow connected it to another service that was compromised, which could've given OurMine access and matches what we've seen in previous hacks.

However it happened, this problem appears to be growing. While hacked social media accounts anywhere are common, there's been a run on Twitter accounts lately, from Katy Perry to Deray Mckesson. We've contacted Twitter to see if there's any information on how this happened, but if you're concerned about your account, here are a few things I can think of that you can and should do.