Is there any way of auto-notifying a poster when their topic has been promoted? At the moment we're doing it manually as it is a massive moral booster, but is easily missed by the member if they're not aware.

I'm guessing by the lack of response that it isn't, it would be a very helpful feature if IPB might consider introducing it, or maybe a coder would like to step in and produce a plugin 

It is not possible out of the box, no, but I did raise your idea as a suggestion to our internal tracker.