We want people to tag, comment and make notes on the images, just like any other Flickr photo, which will benefit not only the community but also the collections themselves. For instance, many photos are missing key caption information such as where the photo was taken and who is pictured. If such information is collected via Flickr members, it can potentially enhance the quality of the bibliographic records for the images.
The flickr folks have some things to say about this as well.
Via Singing Loudly.