This is the block which contains "My Account", "Log In/Log Out" etc by default.
I've seen a few suggestions on how to do this, but I haven't seen anything complete that doesn't involve editing core Magento files that will be overwritten in the next Magento update. Can a suggestion be mode on the best way to do this? I would imagine creating some files in the local folder pool to over ride the default file that would include a local.xml file? A full complete answer that details this step by step would be great, as this doesn't seem to exist. Almost looking for a "dummies guide" to be honest :)