I'm seeing the same issue on Drupal 5.7, Ubercart 1.0beta3... The weights are specified. I tried this with two products. One has attributes, and the other does not. The request to USPS seems to be going through. The response from their server is:
<?xml version="1.0"?>
<RateV3Response><Package ID="0"><Error><Number>-2147219500</Number><Source>DomesticRatesV3::clsRateV3ValidateWeight;RateEngineV3.ProcessRequest</Source><Description>Please enter the package weight. </Description><HelpFile></HelpFile><HelpContext>1000440</HelpContext></Error></Package></RateV3Response>So, aside from a 'metoo', I'm also looking for a solution. 
I'll do a little more digging, but hope someone has an easy fix.



Joined: 01/28/2008