Google has found themselves in a bit of hot water with Google Reader, with a recent update to the program that changes content to be automatically shared. With things you submit to Google Reader, now anyone on your Google Talk list, which can range from people you've added to an IM client or people you send mail back and forth to via Gmail, has access to RSS feeds and other things you've put in. Not everyone might want that, not everyone wants every contact they have able to see what they read.
The controversy is that with this recent update, it defaults to sharing, which concerns privacy advocates and might be the exact opposite of what you want. Many people are telling Google they should make it an “opt-in” feature rather than the default, though Google clearly disagrees.
Of course, Google is known for their receptiveness to users – if there really is a large outcry, they might change their views.