I mean the context bar that is part of stock OpenACS - not sure if dotLRN makes use of it yet (it should though in my opinion, since certain pages are very inconvenient to navigate if they haven't got it). For example while posting this I see this context bar at the top of the page:
Your Workspace > OpenACS Home > Forums > OpenACS Q&A 2 DotLRN Designs (feeback appreciated) > Post a Reply
It's also called breadcrumb navigation.