Hia.

I just tried to do a "cursor to selection" to a specific bone in an armature whilst in pose mode.

The cursor merely moved to the position of the armature. And when doing "selection to cursor" this also acts upon the armature and not on the bone in pose mode.

I use the "cursor to selection & selection to cursor" all the time during building of meshes... and animation of meshes... it'd really help if it worked on bones as well.

Or is there another trick???

We all know that Blender has 2 main modes: object and edit. What I believe is going on is that Blender considers pose mode an object-variant mode and therefore considers the armature as one armature, rather than many bones making one armature. This is something that can be disputed on the bf-committers mailing list. It seems to me like what you are saying is a good idea.