To be honest, I do not fully understand this announcement, but it is causing a lot of discussion in the various forums. In short, the Google Base Blog announced new marketplace and aggregator policies that are going into effect December 1st, 2009. The policy is there to help Google manage duplicate feeds (content) from the same seller, who has their feeds submitted by multiple locations.
Google is releasing a feature named "multi-client accounts" which allows "aggregators and marketplaces to consolidate and manage data feeds and reporting for sub-accounts, submit changes more rapidly, and get more accurate Google Checkout badging at the seller level." So this stops "individual sellers on marketplaces" from needing to a feed to Google Product Search.
There is a lot of discussion on who this will impact, what they should do and how they can prepare. In fact, some are considering dropping eBay and other aggregators to gain better control over their feeds.