Have you been using this setup with Google Checkout and ebay all this time, or just ebay? That part's not clear to me. It would be great if you could do it, but I still have my doubts. How much is the service after the trial is over? The "pricing" button didn't help much to answer that.
Although I'm not sure it would help me in the end. I'm still trying to figure out how Google API works! lol
When the shopping cart sends an invoice, does it show the buyer your googlecheckout company or ebay username? That might get a little confusing if they're different (and frequently are). | 
