The link quoted on the EclipseLink/Maven wiki ends on an Error 403 page on switch.ch. If you are redirected to a better mirror then that would already be the answer.
Just faced the same problem today. It appears that the URL provided on their Maven wiki page http://wiki.eclipse.org/EclipseLink/Maven works. But it works in a weird way: their repository is not indexed so if you try just to add this into pom.xml:
EclipseLink Repo
http://download.eclipse.org/rt/eclipselink/maven.repo
true
and then try to index the repository it will tell you Unable to update index for EclipseLink Repo|http://download.eclipse.org/rt/eclipselink/maven.repo.
But if you also include into the pom.xml this:
org.eclipse.persistence
eclipselink
2.0.0
compile
it will do the work and add the dependency. Not ideal but works.