Last Monday, I had pulled my Boxster S out of the garage, then quickly went back inside the house to lock up. I forgot to fully apply the parking brake, and my car slid back into a small tree. The rear driver's side of the bumper is caved in, and there is one large crack in the bumper, a ton of scratches, and two minor cracks. Thankfully, none of the metal around the bumper is damaged or deformed, the damaged is contained all withing a single area, and the bumper didn't cave in enough to break or crack the break light. The entire damamged area is a little less than 8 or 9 inches wide, and about 8 inches high.

I'll see if I can post a picture later. But anyway, I need to know before I go to the dealer, can this be repaired, or does the entire bumper have to be replaced since it's made out of fiberglass?

your local body shop should be able to repair it. if not, it will cost about 1000.00 to replace and repaint.