Found that there is a BLF for calls in the queue - I've only tried it on a single queue, but it does work. Cant say it will work if an agent is part of multiple queues. Seems there might be a little more functionality on a Mitel/Aastra 6867 set which might allows multiple queues.
*47 *ext (for extension 201 it would be *47 *201)
If an agent knows there's call in the queue perhaps they can get rid of a call a little sooner, or hustle things along.
I've found it works on Aastra/Mitel 6755, 6865, 6867
(edit: first post wasnt keeping the asterisk)