Facebook like photo gallery with comments, tag photo, share etc
To annotate images in Drupal 7: Imagefield Marker
http://drupal.org/project/imagemarker

See also: Image Annotations in Drupal 7

Very good multiple image uploader in Drupal 7:
Media module
http://drupal.org/project/media
(Quick way to get this is to create a free drupalgardens.com account and export the whole Drupal 7 code)

Comments are built-in in Drupal 7 for many content types.

Consider also:
http://drupal.org/project/disqus
(Drupal support for DISQUS a discussion comment system for integration with various social networking sites)

Also: Facebook Comments module:
http://beacon9.ca/labs/drupal-7-facebook-comments

I would suggest integrating comments with an existing social network as their authentication policies (particuarly Facebook's for example) can discourage trolls, spam and provide you with a centralised means of managing the comments, as well as spreading awareness of your site as their comments on your site are seen by their friends in their feeds).