This update is identical to 2.9.2 except that the key's for all shipping methods have been capitalized so that they will be compatible with the change USPS apparently made to the values returned by their API around 11-18-2007. I don't know at this time if this is a permanent change they made so make a backup of your files before changing anything.
For new installations:
* Simply follow the original instructions.
For existing installations:
* Replace /catalog/includes/modules/shipping/usps.php with the new one included
in this package. It is the only file that is changed. (Make a backup first
in case you have to revert to the old behavior)
* Run the script update.sql to modify the configuration table in the database.
Your configuration will be preserved, it just converts them to uppercase.