Tumblr’s dramatic rise has apparently taken a toll on the company’s queue system (aka scheduled posting), and in an attempt to avoid a “fail whale” scenario they’re not only scaling the feature, but promising to wow the world when it relaunches.
Later this week we’re pushing a complete overhaul of the Queue feature with some killer new functionality.
In the meantime though, the existing queue service is handling a volume of posts it was never designed for. To prevent it from becoming unstable and mis-publishing posts, we’ve decided the best course is to take the queues offline and expedite the relaunch. (Tumblr Staff Blog)
Thus far the company hasn’t given any hints as to what the new system will look like, although if I had to guess it might have something to do with solving the international group blog problem (i.e. queuing posts based on a timed countdown rather than a specific time).
Tumblr has thus far not given an estimate of when queued posts will return to the tumblr-verse, although hopefully soon (as manually posting queued posts is not exactly fun).