Twitter bug forces anyone to follow you, but Twitter shuts it down quickly
The fix seems to be involving a bit of a reset at Twitter. Your stream should be operating normally, but every account on the site now appears to have zero friends and zero followers. Twitter may be grabbing a backup of the database from before the bug happened, but there's no official word yet. Basically, there's nothing to worry about, and nobody is going to make you follow their Twitter account.
(Of course, that also means I can't make Conan O'Brien follow me. Bummer.)
Update: Twitter has an official blog post up, declaring the bug fixed.