I think it would be a nice touch to add a comment button to stream posts.

Meaning when you post to a stream and someone visits the post and makes a comment, there would be alike and reply/comment button next to their comment. This would automatically tag them in the reply. Currently, there is only one master comment area and in order to have their name, you have to tag them in it.

See the attached screenshot for an example.

See the second screenshot for an example of how Facebook handles this.

Thank you,
James