UPDATE
At 4:40 p.m. EST, Twitter returned. Original story below.
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According to the site’s developer page the outage is related to the “userstream.” According to Twitter:
User Streams provide a stream of data and events specific to the authenticated user. Note that User Streams are not intended for server-to-server connections. If you need to make connections on behalf of multiple users from the same machine, consider using site streams.
The wonderfully named, DownForEveryoneOrJustMe.com, confirmed the outage.
