I use Google Reader to catalog and organize my various RSS feeds and have been since I dropped NetNewsWire (which Brent Simmons above wrote) years ago in favor of Reeder on my Mac and my two iOS devices.
My RSS feeds are the center of my online activity and I can’t imagine doing what I do online without a single application to organize and read them. I track activity at this site, my flickr account including all of my contacts, various sections of numerous newspapers and news feeds, blogs, photoblog, Apple related stuff, funny videos, and lots more. Google Reader and clients like Reeder and the RSS functionality they use is the single most important part of my computing experience and has been for many years now.
I have no doubt that the authors of the various Google Reader clients (like Reeder) are watching closely and will adapt to whatever Google does, but as Bent says, Google is looking a bit less generous and a bit more self-serving by forcing integration of their social network which may or may not be meaningful associated with RSS feeds.
This announcement isn’t just a reminder of the fragility of the system: it removes some features that people use. Google Reader’s social and sharing features are going away in favor of integration with Google+.