Land-based PLBs are becoming available in the lower 48 states (perhaps specifically the PNW?) after a pilot program in Alaska proved to be successful. They are very similar to the EPIRBs used on ships. Once activated, they are spotted by satellites and a location (if a GPS unit is attached or incorporated, otherwise it uses the frequency to triangulate) is transmitted to Langley, Virginia. They in turn contact local SAR resources to go find the beacon. They have coordinates to find the thing, but the beacon also transmits on the standard ELT freq. long used in aviation to find downed aircraft, so you can find them that way too. They will be pretty expensive for awhile yet. Some SAR groups are starting to train with them now, but I've yet to see one in the Oregon mtn rescue community. The "Mt Hood Locator" is still in use, but it is much more simple, using basically a bear collar system. It still works well, and was in fact used this January to pinpoint a lost group near the summit of Mt. Hood.