The value of the dollar, relative to the pound, rose from 2008 to 2012.
Has the value of the dollar dropped from 2008 to 2012? Yes or no?
Versus what other currency? Because, as Polk pointed out, it has risen against the Pound.
Against the Euro, it is about the same as it was at this point in 2008.
US Dollar vs Euro Chart (USDEUR)
Against the Chinese Yuan, it has fallen, but then pretty much everything has.
Against the Russian ruble, it has remained the same on average, though the ruble's value fluctuated wildly in 2008, so it would change depending on which part of 2008 you were referring to.