I think PC stands for perspective control. I'm not sure if it is the exact same as tilt shift. If it is, it allows a photographer to avoid lens distortion and achieve a greater range of focus. They can also be used to apply depth of field where it would usually be difficult to obtain, like a far away landscape. A good article here.
http://www.luminous-landscape.com/tu...using-ts.shtml
that looks like a nice pickup flar, I am debating if I want a TS or macro as my next lens. I think I would get more mileage from a TS.