It looks like the problem is with their advertising system. They’re adding ads as items within the feed (bound to annoy some people, but something we could live with). Unfortunately, they’re not escaping the ampersands (&), which is causing problems for any feed reader expecting valid XML.
Odd that they would not have noticed this. Anyone want to take bets on how long it’ll take them to fix it?
UPDATE: If you guessed “four days”, give yourself a cookie.