Slashdot linked up this New Scientist article detailing new evidence for an upcoming magnetic field "flip":

By sifting through ships’ logs recorded by Cook and other mariners dating back to 1590, researchers have greatly extended the period over which the behaviour of the magnetic field can be studied. The data show that the current decline in Earth's magnetism was virtually negligible before 1860, but has accelerated since then.

The trend seems to indicate a total flip in perhaps 2000 years or so. During that time, the Northern lights will be visible across the whole planet and solar radiation will be "much more intense" at the surface. So ya better stock up on sunscreen, ya hear?

Personally, I blame Condi Rice.