I don't think it's a good idea to let administrators change the admin block with html, perhaps let the admin write an optional instruction over hard-coded Admin and Logout links...
Removed admin block functions
Seriously, this is a good idea. Put static Logout and Login Links for the admin menu in the database BUT allow the administrator put a Title in above it IN plain text W/O HTML i.e. htmlspecialchars function. You see, that's one place where we don't need to worry about someone messing up the menu by forgetting the a href.
Brian W. Brown