Just a note:
/dotfolio is an instance of dotfolio
/$username is an instance of dotfolio-ui
dotfolio should really be a singleton, in that you only want one instance of it. Whereas dotfolio-ui is the user's site, and should be instantiated numerous times for each user.
I know it is laziness on my behalf for creating the user space dependency on /, but there was good reason to. Dotfolio is meant to be a student centric tool, and therefore should be situated externally to dotlrn. DotLRN is course centric, in that resources only exist for the duration of a course, before they are either reset or archived.
Having dotfolio mounted externally to dotlrn means that students can have access to their site for the duration of their degree as oppose to only the duration of a course. It gives the student more time to make "connections" for deeper learning, which is fundamental to the principles of constructivism (for those that are into the whole pedagogical mumbo jumbo :P ).