My students have joined the Group. Now when they go to their web-logs, after logging in to their Diigo account and setting “Show Annotations > Show Group Annotations” on their Diigo toolbar, they will see the highlights of specific passages from their writing that I have left (and I can start students doing this too, it occurs to me in a very attractive flash), and my annotations will pop up on their screen when they hover their mouse over the highlights.
I love this idea about using diigo instead of comments to markup students blogs. I don't think I've seen this post before.
And since they’re using anagrams instead of first-name usernames on their blogs, there’s less of a chance of any embarrassment resulting from this “public feedback”–with “invisible ink.”