I copied the terms of the offer below, but by my interpretation, it doesn’t specify that a purchase has to start with Google Product Search in order to be eligible. (I had not heard of this Google feature before now.)

Rather, by my reading, as long as the store you buy from is included in Google Product Search (even if you didn’t find the store that way) then you should be okay. Sort of like a promo that says “10% discount if you say you saw it in the yellow pages”… if I tell you to go to the store and ask for the yellow pages discount, they’d give it to you. My interpretation. I will ask them for clarification.

Here are the full terms, with the questionable phrase highlighted:

*Terms: Offer expires on December 31, 2007 (11:59PM PST) and Google may terminate open enrollment in this offer at any time. Purchases that occur prior to the date of registration are not eligible for mileage and total miles earned through this promotion cannot exceed 10,000 frequent flyer miles. To earn miles, participants must be located in the United States and specify a valid frequent flyer account. Registration authorizes Google to contact the participant by email regarding miles earned through this program. A given frequent flyer account may not be associated with multiple Google Checkout accounts and if a participant enters multiple mileage accounts, all miles will be credited to the most recently entered frequent flyer account. Only direct purchases from stores that display the Google Checkout image in Google Product Search will accrue miles. Invoicing transactions, resale transactions, and any attempt to earn miles through fictitious or otherwise invalid transactions, as determined in Google’s sole discretion, are strictly prohibited from earning miles. Google reserves the right to suspend the program for individual users in the event of violation of Checkout terms or offer abuse as determined by Google. You must be a member of at least one participating airline awards program to redeem your frequent flyer miles. To enroll, visit the applicable airline awards program website. Your airline awards program number is required for the redemption of your frequent flyer miles. The terms and conditions of the applicable airline awards program govern the use of your frequent flyer miles.