Infosyncworld, among others, noticed that GPS, er, sucked in December - and posted that it was due to a solar flare. My own local paper elaborates with a story from the AP detailing how we can expect more of this excitement in the future:
The Global Positioning System, relied on for everything from navigating airplanes to transferring money between banks, may be threatened by solar flares, scientists warned on Wednesday.
The big problem is that solar flares occur in 11 year cycles - the next one is due in 2011. During our last peak, in 2000, GPS wasn't as widespread as it is now. I've heard from various doomsayers that your average GPS unit will experience 2011 in the same way that a newborn experiences light: bright, fuzzy, confusing, and not able to really identify anything specific.
So get your GPS fun in now, before the sun starts having its way with it.