What is RSS?
RSS (Rich Site Summary) is a format for delivering regularly changing Web content. Many news-related sites, Weblogs, and other online publishers syndicate their content as an RSS Feed to whoever subscribes. All subscriptions are free.
When you see this symbol it indicates that the Museum has set up a feed to deliver the latest content right to the feed reader of your choice. Possible feed readers include, but are not limited to, Sage, RssReader, FeedDemon, NewsFire, and Google Reader.
For more information on RSS and various feed readers, check out this link: http://www.whatisrss.com