Will anyone tell me why is the dollar appreciating?

Wall Street is in a state of turmoil.
Unemployment rates in US are on the rise (HP has today announced a downsizing of 25,000 odd employees).
And if the value of currency is determined in open market, will someone tell me who is upbeat about the US economy? And why?

PS: I did get the answer to this one. See Why is Dollar Appreciating?
Later on, the main stream media caught up. What fun!