You know it's weird... I've tried to import my blog into FriendFeed a few times over the past few weeks since they launched, and I keep getting the same error as I captured in the above screen shot. That link is mapped to FeedBurner, but I can also put in my direct feed URL and it won't work either.
I'm not sure what the deal is - I thought it may have been a bug that they'd have fixed by now. I've got a valid Atom feed, and it's being served Google, so it should be up and accessible. Is it just me, or is this common? Everyone seems to have all in a tizzy about the service, so it'd be interesting to see how it actually worked with my primary outlet.