Moving the weighting from one bone to another, in the same armature?

I’ve been working with an importer that worked fine for the most part, but I ran into a problem when the weighting for a leg bone somehow ended up on a nearby control bone instead. How can I take/copy the weighting from one bone in the armature, and get it on another bone? I’m using Blender 2.69.

One way to do it, is to rename the vertex groups.
With the mesh object selected, check Properties > Mesh > Vertex Groups panel.
Double LMB to rename.

Rename the one with the correct weights, so it has the correct name for the bone.

This has worked great, thanks for the help! I hope there’s no side-effects though, such as other things breaking, but it doesn’t look like it.