This recent piece
in the NYTimes describes the decline the intensity of the Earth's magnetic field (actually what it describes is the content of talks several geophysicists gave to this effect at the ongoing biannual national meeting of the American Geophysical Union
). The gist of the piece (and I imagine of the talks) is that we may be seeing the first stages in a flip of the Earth's magnetic field. If this were so we might expect that at some time in the next several thousand years the Earth might undergo a couple of thousand years with a minimal magnetic field before an inverted one (north would, in some sense, be south) started to gain intensity.
In these times of changing geomagnetic fields it is worth noting, I think, that there is absolutely no evidence in the geological record suggesting that this time of low magnetisim would result in an end of all life as we know it type scenario (as I'm sure you remember from this summer's THE CORE
). In fact, the paleontological record seems to suggest no significant extinction events ever accompanying a reversal of the Earth magnetic field.