Looks like Google Base is officially live. Check out the blog post and then play around with Google Base here.

Right now, there are two ways to submit data items to Google Base. Individuals and small website owners can use an interactive user interface; larger organizations and sites can use the bulk uploads option to send us content using standard XML formats.

Rather than impose specific schemas and structures on the world, Google Base suggests attributes and item types based on popularity, which you can use to define and attach your own labels and attributes to each data item. Then searchers can find information more quickly and effectively by using these labels and attributes to refine their queries on the experimental version of Google Base search.