There isn’t a page on Twitter (including their blog) that can be accessed as I write this (3:30am PST Thursday). It may just be sugar coating on yet another period of downtime; an alternative to the Twitter downtime bird that replaced the Twitter cat some time ago, but if it is, it’s the first time I’ve seen it. On the other hand, something might be going on at Twitter: more stable servers perhaps? or even a new feature launch? Watch this space.
Update: Twitter back up as at 5am PST. A notice on Twitter states that Twitter would be down for 2.5 hours from midnight, looks like they were 50% of the way there is terms of downtime. At the time of writing there is nothing on the Twitter blog explaining the reason for the downtime. Looks like a regular outage with sugar coating.