I just finished installing Gregarius because I wanted to access my feeds no matter where I was and have a consistent read/unread status across all machines. Before I used to use RSSOwl, which is a great app, but when I got home I would have to go through and "read" items I had already read elsewhere. I had tried Google Reader, but there weren't enough features.
Sure enough, as soon as I installed Gregarius on Dreamhost one of the first feed's was Robert Scoble's. It was a brief on the new Google Reader features. I'm going to try out the new Google Reader, but for now I'll leave Gregarius installed, as it's a very nice application.