Flickr iPhone App
New official iPhone Flickr client (iTunes link). I love the home screen interface; it's a really nice design. You open it up and it shows you Ken-Burns-style zoom-and-pan animations of your friends' photos. But man, is this app crashy for me. Crashed when I tried to upload an image. (Then it worked.) Crashed when I tried to snap a new photo from within the app. Tried twice again, crashed twice again. Three strikes and it's out.
And for browsing pictures from friends, I'm still not sure it's a better overall experience than the iPhone-optimized m.flickr.com web site. For the social aspects of Flickr, this app just doesn't feel very Flickr-y.