I think libraries can use this tool both as a learning activity and as a promotional device. Libraries can use flickr to show users how to manipulate images and inspire those inclined to the visual arts to create projects of their own. This way, libraries can connect artists or aspiring artists with the capabilities of the web.
Additionally, I believe this tool can work wonders for libraries as a promotional tool. Libraries can build photo-blogs promoting library activities, not just by posting pictures of the activities but also mashing the pictures with information useful for those who want to attend the activities, like weather and traffic conditions, links to personnel in charge of the activity so questions about the activity can be asked in real time, etc.
'Til next time,dudes!