Currently, chatter shows badged comments, the comments of people that you follow, and comments on posts that you have shared.
Soon, this will change.
After the next update, chatter will show badged comments, the comments of people that you follow, and comments that they have shared.
That means that ‘upvoting’ (circledotting, blooping, etc.) a comment will send it into the chatter feeds of the people that follow you. Comments will be shared.
In addition to this change, just as on posts, comments on your chatter page will feature "shared by" information indicating who shared the comment, and who shared it with you.
We are giving a pre-announcement for this update, because it means that comment 'upvoting' will no longer be anonymous. If you'd like to see the comments that you have shared, follow the link below, changing 'mk' to your username:
Only you can see the comments that you have shared at this time.
We are making this change for two primary reasons: 1) Chatter and feed functionality will be similar, and the sharing mechanism for posts and comments will be similar. 2) It is our hope that removing anonymity from comment support will increase the support for thoughtful comments, and decrease the support for less-thoughtful ones.
As always, feedback is much appreciated.