This is an interesting article on the shifting of the Earth's magnetic field. I included the google link so you can click on the article link from the search engine. Due to registration reasons, you cannot access the article any other way unless you are registered with the NYT.

Marilyn Farhat.

The collapse of the Earth's magnetic field, which both guards the planet and guides many of its creatures, appears to have started in earnest about 150 years ago. The field's strength has waned 10 to 15 percent, and the deterioration has accelerated of late, increasing debate over whether it portends a reversal of the lines of magnetic force that normally envelop the Earth (read more)........

http://www.google.com/search?hl=en&ie=ISO-8859-1&q=compass+point+south