How you have to do it, is that you have more than one copy of that base dashboard as well. Regular users see one copy of it, and power users another. The only difference between the two is that the drilldowns go to the corresponding drilldown views, which have similar permissions. To expand a little bit on the "permissions", you go into Manager > Views and you use the little "permissions" links to set which roles can see which views.
As far as just getting a $user.role$ key or something courtesy of Sideview Utils, and forking off of that in one dashboard, no I'm afraid there isn't. ValueSetter will be getting a way to set certain values conditionally, sometime later this year, and I might one day submit to the user requests for such a $role$ key, but the best way to do this is just duplicating both views and setting appropriate permissions in Manager as described above.
