Nice thread. I joined simply to chime in.
I dont use The Old Reader, I use a WordPress RSS aggregating plugin. As of September 16 or so, items have stopped fetching. They started working again for a few hours yesterday, only go be blocked once again.
Here's the thing, though:
If you use an RSS validator merely to check an RSS feed, they can't even read them either. Search Google for "validate rss feed" and try a few Craigslist feeds; you'll get error messages.
Furthermore, if you use an RSS generator (those tools that "create" an RSS feed out of any page), they dont work either.
However, the above work fine during those few hours that my plugin can fetch RSS feeds.
So, the Craigslist issue seems to be very wide, not just limited to one or two readers.
I hope this info has helped. I feel helpless and cant wait for this issue to go away, assuming that it will.