I'm playing around with evaluating Flock right now. I wasn't too hot on it 9 months ago but ever since I saw a photo integration with PhotoBucket and realized they also have Flickr support, I decided to give it another look.
So far it's a mixed experience - not quite Firefox, not quite Camino, not quite Mac OS X (aka. I want my emacs bindings dammit!), not quite a RSS Reader like Vienna. All the elements are there and it's gonna be a tough call from a UI perspective as to how to integrate it all together: blogs, photos, news, web, favorites, etc.
If all works well - this will go out to my mashup blog!
Blogged with Flock