iPhone/iPod touch: There have been third-party apps like Flickit to upload iPhone photos directly to Flickr, but Flickr's own app has hit the App Store, combining tools for uploading, tagging, search and set organising in a crisp-looking package.
The main page, shown at top, is where you get the most functionality, with an ever-present upload button in the upper right, beautifully cascading random images in the main frame, and quick access to your photo stream and those of your friends. Tapping a photo shows a pretty big view of the pic, and clicking for an even larger view gives you a full-screen, scroll-around vista.
Image uploading is also an easy and slick affair, with clearly understood privacy controls and big areas to tap to add tags, descriptions, and set inclusion. More interestingly, it's probably not a coincidence that this app is landing in the App Store one day before Apple likely introduces iPod touch models with 3.2MP cameras..
Flickr is a free download for iPhone and iPod touch models running at least the 3.0 firmware. Uploads and profile features require a free Flickr account.