in my school, lin gun is an integral part of each class; however, some classes concentrate on lin gung more. a beginner student goes through the general lin gung exercises first, intermediate and advanced students have a specialised lin gung programme.
short overview of the tools/methods we use in my school:
http://www.lghk.org/en/curriculum/lin_gung.htm
of course strechting, cardio, plyo and other aerobic exercises are part of lin gung. i would not call them modern, as most of them were a part of various traditional martial arts since the beginning of time. the new thing is the scientifical explanation how the things work and more detailed training protocole of developing the various types of power (maximal, speed, explosive, endurance; periodisation etc.)
btw. i wouldl ike to note that Hung kyun is very lin gung based system, just look at the first parts of gjffk, fhsyk, syk or whole tsk, weapons etc.