ars technica: Nobel Intent - 2010 Feb 10
BBC: Sat-nav devices face big errors as solar activity risesOur satellite navigation systems are about to take a pummeling from the Sun. The Sun is on schedule to experience an increase in solar activity that will interfere in a number of ways with the communication between satellites and navigation receivers on the ground, resulting in some potentially annoying outages and errors.
After a period of low solar activity, the Sun's radiation is scheduled to rise again in the coming months. The heightened activity includes an increase in the occurrence of solar flares, which contain radiation in most wavelengths of the electromagnetic spectrum as well as high-energy particles. While the effects of the flares are not incredibly strong, it doesn't take much to mess with the satellite navigation systems we have in place.
Researchers say the Sun is awakening after a period of low activity, which does not bode well for a world ever more dependent on satellite navigation.