Any piece of content should be simply and easily shared to anyone or any community. A single icon with a click, a field to specific who/where, and the rest should be automated. Addition of comments could be optional. Best case would capture the basics of the item being shared (first image, first 250 characters, etc.) to append to the link that would then be posted/shared to others. Of course, identity awareness needs to be implicit so items can't be shared if the recipient(s) do not have the needed permissions.