Perhaps because of the popularity of sites like Flickr, Picasa (owned by Google) has created the hello file-sharing system.
Hello doesn’t appear to be a direct competitor to other photo-sharing sites, but rather a replacement for e-mail and traditional IM networks for the niche market of sharing photos with particular individuals (as opposed to the public at large). Because of Picasa’s relationship to Google, hello is integrated with Blogger in addition to the Picasa photo software, making Picasa an excellent choice for bloggers using Google’s service.
Unfortunately, this is only available to Windows users for the time being; that’s all well and good, but the maintainers of hello’s website would do well to make that fact more clear before one signs up for an account.