> So I don't quite understand is the falling price because mtgox is down for maintenance
It had already dropped considerably (below $130, IIRC) from the ~$200 it had bounced back to from the earlier drop from $266 by the time MtGox shut down trading. The shutdown of trading at MtGox may have encouraged further decline across other markets, but it doesn't seem to be the original source of the decline.
> if so why does it have that effect, I don't run into the street and burn my cash just because the banks are closed on Sundays
OTOH, you might demand more dollars for goods (or just be less likely to accept them at all), or, on the other side, accept less good for dollars and be more eager to get rid of them if the main outlet for trading dollars for other currency shut down on a day that it would normally have been open (e.g., not a regular Sunday office closure) after a day of high volatility trading where the dollar had lost half its value before the trading was shutdown.
It had already dropped considerably (below $130, IIRC) from the ~$200 it had bounced back to from the earlier drop from $266 by the time MtGox shut down trading. The shutdown of trading at MtGox may have encouraged further decline across other markets, but it doesn't seem to be the original source of the decline.
> if so why does it have that effect, I don't run into the street and burn my cash just because the banks are closed on Sundays
OTOH, you might demand more dollars for goods (or just be less likely to accept them at all), or, on the other side, accept less good for dollars and be more eager to get rid of them if the main outlet for trading dollars for other currency shut down on a day that it would normally have been open (e.g., not a regular Sunday office closure) after a day of high volatility trading where the dollar had lost half its value before the trading was shutdown.