RSS feed not being pulled

Even though my blog’s content is being posted when it is posted, for some reason the feed isn’t working. Suddenly none of the sites my feed is hooked up to is pulling the new content even though I’ve validated the feed and apparently its working.

http://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Ftowerofbabel.com%2Ffeed%2F

Any idea what’s going on?