I just was at Google Base browsing the FAQ and noticed they have a little desktop program called Google Base Store Connector. It allows you to publish your products from eBay stores, Yahoo stores and OSC stores, pretty neat! Here's the link: http://www.google.com/base/storeconnector

Too bad it doesn't support ZenCart yet. I just submitted my suggestion. I think support for ZenCart will be added in due time, after all ZC is superior to OSC and has a very large user base, just wished Google would realize this and give priority support to ZC. :)

Anyone who wants to submit a suggestion telling them you want support for ZenCart can do it here: http://base.google.com/support/bin/request.py?contact=1