Kev,
The way it was looking last night is that the Fed might do a hefty rate cut today. Actually, they're still talking about that. That will make the dollar drop more (usually) making the Yen even stronger compared to the dollar. The Yen's movement has a huge affect on markets. A lot of selling off of Japanese companies, then spreading around the globe, happens when the Yen gains in value.
But, the effect might not be as bad as I thought, since the speculation is that Japan will cut their rate on Friday, back down to 0.25%!!! The cheapest loan in the world! Combined with the U.S. Fed rate cut, the balance between the dollar and the Yen might even out.
The good thing about a stronger yen is that Japan can buy more of our exports, which I think food is one of our biggest to them. Other than that, a stronger yen has been pretty bad for stocks over the past couple years.