Within the Copy Artifiact plugin you can select "Sepcified by permalink" and after installing the Promoted Builds plugin it lists as the last entry "Latest Promotion ...".

What I see now as the Latest promotion is the promotion link to the project I'm in, instead of the referenced link specified in the Copy Artifacts from another project's referenced project.

When I last upgraded Jenkins and the plugins a couple weeks ago this stopped working.

It looks like a similar bug was reported on 9/9/2012: JENKINS-15086.