When the USPS updated their Web API on July 28, 2013, it caused the nopCommerce USPS plugin to dispaly jibberish for the available shipping methods.
Example:

This download contains the nopCommerce recomended fix for this issue. See the post on nopCommerce here.
After fix:

See help on NopCommerce for installing a plugin here. (though all of these steps are not required if you are replacing the USPS plugin)