Fotonotes rocks! Glad to see that Flickr is using it rather than re-inventing the wheel. I hope other apps start using it! From Stewart's comment on Flickr Notes - visually annotate your photos:
Thanks Roland! Hopefully it will be everywhere: we're committed to helping to develop and supporting a standard for annotation, based on Greg Elin's Fotonotes stuff. Once there is something to be compatible with, Flickr will be 100% 'Fotonotes R/W' (read/write) compatible.