Comments from Japanese Finance Minister Sadakazu Tanigaki that Japan had grown resilient to the stronger yen gave the currency another boost in the European session, lifting it to 103.45 yen to the dollar -- its highest since April 2000.

This is important because people have been talking about about 105 yen to the dollar as a resistance level for some time. As Kash notes on The Angry Bear:

Such rumors have been floating around for over a week now, but the fact that they persist and seem to be gaining credibility may be significant. The telltale sign will be if they allow the yen to fall below about 105 yen/dollar, since that seems to have been where they've dug their heels in up to now

and

The drop in the yen/dollar exchange rate below 105 would have a minimal impact on the US economy, at least this year. However, given that Treasury data shows that Japan has recently been buying a net of $20-25bn in US government bonds per month, if Japan were to stop buying US treasuries there could be an effect on long-term interest rates. Exactly how much long-term rates will rise is the $64,000 question.

Note though that a crash instead of a decline could result if people start deciding the dollar is not a good long term investment. That would have immediate consequences.