Currently, only articles in the "Featured News" tab of each section are available as RSS feeds. Below are links to the available RSS feeds (if there are others that you're interested in, write me):
All
Every featured article from every section of the site.
Sticky
The main article from each section (pretty much what you see on the left column of the homepage).
Homepage
Every featured article on the homepage except the left column (see above).
Other Sections:
World - U.S. - Business - Movies - Entertainment - Sports - Living - Travel