This is already a subtask, so I can't add a subtask...so just a comment
A requirement for completion of this for GA needs to be an update to the HTTP chapter in the Clustering Guide. So we'd need a 5.2 version.
We should rip out the mod_jk content and replace with mod_cluster content. Add a very short section on mod_jk, mostly referring people back to the 5.1 version of the Clustering Guide.