Clay Shirky writes in Many-to-Many: Notes from ITP: Flickr-as-web-services edition about my current obsession, Flickr, and has some neat stories about how he's seeing people use it. There is a great story he tells of a group of people sending a goodnight message to someone via a photo of a whiteboard that was sent from the time the person left to when they arrived at home and checked their Flickr account.
I'm almost embarassed to admit that I've been using Flickr on my new phone to check for new comments and images. It's tiny and hard to make out detail, but I still occasionally will do it.
Unfortunately my cell phone provider, Aliant, boxes in photos that I take in HTML and don't actually let you attach images to email, which means that I can't moblog to Flickr with my cameraphone, which is a pain.