Yakatz, I've responded to your ticket in support with the solution. Thanks for pointing that out, it was a great help to us.
For the rest of the users having the same problem and if you have the source, please do this simply change in your Googlecheckout.cs, inside GetRates() method.
from:
Code:
Address xAdd = Customer.Current.PrimaryShippingAddress;
...and change it to:
Code:
Address xAdd = cart.ThisCustomer.PrimaryBillingAddress;
Otheriwse, submit a ticket to support so we can send you the updated assembly. I know you've VOTED for public patch repository, but until we haven't figured out the best way to handle that, you'll have to get the patch to support. thanks