Looks like the feed is updated automatically from RSS feeds or some other source. The latest tweet doesn't fit the template, so I'm guessing the "hacked" theory is correct.
Once you start to get big, hacking and spam surely follow... It'll be interesting to see what the story is here. Is every twitter account hackable? Are they going to start implementing some sort of spam filter? or a method to report spam?
You can report spam to the @spam user. That's only effective against users who are spamming, however. It doesn't really help in the situation where an account has been compromised. I strongly doubt "every twitter account is hackable"; someone probably just got hold of the passwords of the accounts in question.
EDIT: looks like more accounts are being compromised. Maybe someone has found a hole in twitter's servers. Or, a disgruntled employee decided to have some "fun".
This is of course a fair point. I haven't seen the SSL version of the site encouraged or even documented anywhere. I suspect it would take down their current server infrastructure if all users suddenly switched to SSL access.
Looks like the feed is updated automatically from RSS feeds or some other source. The latest tweet doesn't fit the template, so I'm guessing the "hacked" theory is correct.