The last few days I have been getting complaints here and there about my RSS feeds failing for people. After some looking into it, it seems the problem might be due to Jetpack's Shortcode Embeds -- specifically the [audio] shortcode.
I created a test site to test my theory: http://jetpacktest.aspiringindie.com/. It's running Twenty Eleven and Jetpack, with only the Shortcode Embeds component activated.
You see three posts, with the second post down using the [audio] shortcode. If you run the feed through an RSS validator (like this) you'll see that the feed is valid but includes a couple of recommendations. However if you try to add the same RSS feed (http://jetpacktest.aspiringindie.com/feed) to Google Reader you'll see the problem I'm running into. Only the list view displays the posts at all, but no excerpts when you click them, and the summary view displays nothing at all. It acts as though the RSS feed is broken, although it's valid.
I'm deactivating Jetpack's shortcode embeds for the moment. It's a bummer that the shortcodes will all display as text everywhere on my site, but that's preferable to breaking all the RSS feeds that contain them. At this point I'm really just hoping the RSS feeds, once fixed, will update and work again in Google Reader without having to be re-added. That would hurt.
Let me know if there's any other information I can provide to help debug and fix this one.