This is just a few quick notes on the new update for Magento version 1.6.1 as well as the new changes in the Google Merchant feed. Google Merchant or Google Product feed was formerly the Google product feed known as Google base. You can view some of the changes that Google Merchant is requiring here: Google Merchant changes.
If you have a version of Magento Community Edition that is 1.5 or below, I have not found a solution for converting the Google base feed that will work for you. If anyone knows of a solution, let me know and I will post it here.
In a nutshell, Google seems to be dropping a few identifiers that are universal like: quantity, feature, manufacturer, genre, featured product, year, author, edition and then adding a few more unique identifiers like: additional image link and google product category.
It seems that Google is also trying to develop their own taxonomy to include (and presumably exclude) products by category. Also, I can’t help but think that the exclusion of brand names and model names in the product feed is a continuation of their proposed changes to their ranking algorithm in which they stated that brand names will start to play a more important role in the SERPS.
The logical extension of this is that in a perfect Google world, Manufacturers (and their brands) should rank above web savvy marketers if they are the source of the product. By requiring a unique identifier for each product that is uniform, they are also setting up the ultimate comparison shopping engine. Requiring this conformity across competitors will squeeze the profits out of the smaller marketers as drop shippers and small independents will compete for lower prices (and higher Google fees) in order to make a sale.
In the short term, keep your products in the various shopping feeds, but keep your eyes on the horizon for a new opportunity when it comes available as this current model is unsustainable for more than just Google.
As far as making sure that Magento works with the new Google product feed, make sure that you add an attribute for condition which should have the appropriate values as a drop down and the value NEW as selected. Also, make sure you have the new availability as a drop down with the following attributes: ‘in stock’, ‘available for order’, ‘out of stock’ and ‘preorder’.
If you are hoping that you can send all the attributes on a complex or configurable product I would suggest starting with the Google product feed requirements and then working backwards to your attributes as the reverse is often very complicated.