Los Angeles Center (Palmdale CA) [ZLA]: September NOTAM #12 issued by
Gps Notam OA [GPS]
GPS is unreliable and May be unavailable within a 317 nautical
miles radius of 360056.3N/1173627.8W at FL400, decreasing in area with
decrease in altitude to a 267 nautical miles radius at FL250, 195
nautical miles radius at 10000 ft. mean sea level, and 186 nautical
miles radius at 4000 ft. above ground level. the impact area also
extends into the Mexican FIR 2000 - 0100 daily effective from
September 10th, 2007 at 01:00 PM PDT (0709102000) - September 15th,
2007 at 06:00 PM PDT (0709160100)

They're are up to it again, with our tax money.
My planned flight tomorrow may have the same problem, and it's
possible through Saturday. Last time they announced this, the GPS
blocking was hardly used, probably didn't work. Seems the jamming
system works now.
Jim