Does the android market use your merchant API callback URL during the Google checkout process for paid applications? -

If I have an paid app on the Android market, then my merchant API callback URL will get a hit when the customer checks out ? I am wondering how businessmen / vendors / developers have secured their applications for the Android market.

I used Google Checkout before applying a custom integration, so I understand how it works. Whatever I have seen is not visible anywhere, if any, merchant / developer integrates with the Android Market checkout process? I understand that the market uses Google Checkout, but in that situation the market hosts the checkout process and not the dealer, so it is not clear if they give a call to your URL.

So where's the hook? Am I assuming that this merchant API callback URL is?