Thanks to Roger, G3XBM for the link to PA1B's QRPp page. QRP operation is operating with an output power of 5w, QRPp operation is operating with output powers down in the mw range. Bert, PA1B has some nice links to this kind of operation, and includes some designs for 20db attenuators that are easy to build and effective. These can step your 5w QRP rig down to just 50mw, or the FT-817 on minimum power down to a teensy 5mw. Roger did 1310 km using just 5mw on 80m using the WSPR mode, which I think is pretty amazing.
Bookmarked for future reference.