Alex Iskold and Richard MacManus have done an excellent job of comparing photo sharing webservices. They provided a handy table with an overview (see below), as well summaries of this and that.
Note though, that all webservices were compared feature-wise only. Upload and storage limits, as well as access speeds were left out. Also there was no mention of free versus commercial offerings (like, for example, Flickr Pro account).
Still, this is one excellent review which provides a clear picture of what is out there.