Twitter goes down, what’s the fallback service?

So Twitter is experiencing an apparent DOS (denial of service) attack. That begs the question: If twitter goes down, and twitter is the main way people get their updates, how would anyone know? Since, obviously, you can’t tweet out that Twitter is down, where do you turn to get a mass message out to all your friends that they can no longer follow you on twitter until the issue is resolved? Read more…