Google today announced some changes to data requirements and feed specification for Google Product Search listings, These changes won't apply to Google Commerce Search or AdWords ad formats.
For Feeds Targeting the United States, United Kingdom, France and Germany:
Unique Product Identifiers [required for most categories]: With user reviews, prices, related items, and videos, "product pages" help users make decisions about what to buy. Starting May 3, Google will require unique identifiers for all products except apparel and one-of-a-kind items. Products without unique product identifiers mayn't be listed in Google Product Search, though the feed mayn't be disapproved. More Info: Help Center.
Shipping Information [required] When shoppers are trying to find the best deal, online or offline, they need to know the full cost of an item - including the cost of shipping. To help them accurately compare prices, Google'll begin requiring shipping info for Google Product Search on June 6th. "After that date, the company may disapprove feeds from accounts that don't include this info. More Info: Help Center.
For Feeds Targeting the United States:
Tax Information [required]: To ensure that shoppers have a seamless experience when they click through from Google Product Search to your site, Google is making tax information required for all feeds targeting the US. As we're doing with shipping cost information, we'll be making this change on June 6th; after that date, product listings that don't include tax info at the account level, or in the "tax" attribute, may be rejected. More Info: Help Center.
New Sale Price Attributes [recommended] Shoppers everywhere love sales. To help make sure your sale price is included in Google Product Search, and for the right duration, Google's adding two attributes to the US Product Search feed specification, "sale price" and "sale price effective date." The attributes are recommended for the items that you have put on sale, but aren't required. If you do include these new attributes, you should continue to provide the "price" attribute with the non-sale price from your website. More Info: Help Center.