The Google Feed API allows you to do exactly that by using FeedFetcher, the same feed caching and sharing mechanism found in Google Reader.
Some more technical details:
· Data can be passed using either JSON or XML
· The AJAX Feed API only provides access to publicly accessible feeds
· Just about every feed format is supported, including Atom.
If you’ve used other Google Ajax APIs you’ll recognize some familiar patterns and it shouldn’t be too difficult to get up to speed. For Newcomers, here are the documentation..ojvcentral