Google has announced a brand new Shopping API that will eventually replace the Google Base API.
Google Base was the method Google allowed merchants to add their products to Google Shopping (which had five or so names in the past). Now, Google switched these merchants to the Google Merchant center to upload their products that way. Google announced that the API methods they used via Google Base will be discontinued, aka sunsetted, on June 1, 2011.
Shopping Content API:
The Content API for Shopping lets you programmatically manage the structured data items you upload to Google for use in Google properties such as Product Search and Web Search.
Shopping Search API:
The Search API for Shopping makes it easy for developers, Google Affiliate Network publishers, and Google Commerce Search customers to build innovative applications using product data. The API simplifies access to product data and is optimized to deliver the most relevant product results.
Ronald from the Google Shopping team said in a Google Merchant Help thread said:
We are pleased to announce our newest addition to the shopping family -- simple yet powerful programmatic interfaces that enable retailers to upload their content to and query data from Google. The new Shopping Application Programming Interfaces (APIs) have two main components: Content and Search. As part of this launch, we're are also sunsetting the Base API and replacing it with these new Shopping APIs.