Google Webmaster blog has made a official announcement, that they are using RSS feeds to discover content:
Google uses numerous sources to find new webpages, from links we find on the web to submitted URLs. We aim to discover new pages quickly so that users can find new content in Google search results soon after they go live. We recently launched a feature that uses RSS and Atom feeds for the discovery of new webpages.
I am not sure, but Google has been scanning RSS feeds for quite sometime now. In the past few months, I have seen our feed URL http://feeds.techie-buzz.com/techiebuzz being indexed faster than the regular URL.
What has your experience been with Google indexing RSS feeds? Do let me know about them through your comments.