QueueListener extension point?

[blalor]

Is there an extension point for being notified when an item is added to the 
queue?  I see the QueueTaskDispatcher, which allows vetoing of a Queue 
item, and the QueueSorter, which has access to the entire queue, but I 
don't see anything that would let me know when an item has actually been 
added to the queue, regardless of position.  Does such a beast exist?