I've just received the following email from Google on April 1st with further requirements for Google Base.

Does this module support these requirements or will it be updated to accomodate the requirements?

Thank you for participating in Google Product Search. We are reaching out to you to inform you about important changes we’re making to our Product Search attribute requirements for unique identifiers and tax and shipping information.

Starting May 3rd, 2011, we’ll require your product listings to include at least two of the three unique identifiers (Brand, MPN, GTIN). In order to provide as much information as possible to our users, we need your help in matching your products to our "product pages", where users are able to view useful data such as product specifications or reviews. While these attributes will not be required for your data feed to process correctly, they may prevent your items from appearing in Product Search results if not included. For more details, including what specific identifiers you should include for each category of item, please see our Help Center at http://www.google.com/support/merchants/bin/answer.py?answer=160161

Starting June 6th, 2011, we’ll also require your product listings to include tax and shipping information to provide buyers with important price information. This information will be required at either the account or item level (in the “tax” or “shipping” attribute) in order for your items to process and appear in Google Product Search results. For instructions on how to include tax and shipping information, please visit http://www.google.com/support/merchants/bin/answer.py?hl=en&answer=160162