Consider Rook as a base layer upon which other frameworks can be
built. For instance, Hadley has stated that he'll be porting his
sinartra package to Rook, and John Verzani also has a framework of
sorts with his gWidgetsWWW package which he just ported to Rook.
So, something like a django or a ruby on rails for R is needed. That's
a good place to think about session management, database abstraction,
etc.
Jeff