"Your post has been carded by so-and-so!" sounds like Mafia Wars spam though :), I suppose 'shared' or even 're-shared' would work. One issue I can see being: what if the person updates the post? To avoid things being spammed I think you'd have to record the relationship in the database and have a boolean store if the other user has been notified -- this should persist across edits, so even if it gets removed and re-added it does not trigger another notification.
And if you have email notifications on? :P But yes, ideally that is how it would be presented. Like I said, the main issue is you'd have to track these cards to make sure you're not spamming users and that the feature doesn't get abused. For example, what happens if someone makes a post with 100 others embedded? Is that possible? What if it's all the posts of one user, would it notify and email them 100 times?
I would hope the shout-out system has some form of protection in place, again to me this would be some relationships table somewhere saying this post mentions this user and a boolean saying if a notification has been sent. Let's try Cedar War Cedar War. Well wasn't that interesting! It sent me two notifications, but updating the post even to the point of removing and re-adding the mentions in a different order did not trigger new notifications.
I think it is on the spreadsheet. It's on the list (again)... It's just one of those super low priority things that kept being put off. I think mk is actually on it now.
Oh it will be. The problem here is that you can force Hubski into sending too many emails, this may exhaust any mail allocation that the server has but more likely will get Hubski blacklisted as spam -- blocking new users from signing up as they can't verify their accounts etc and incurring financial expenses to mk as he'll have a rough time getting un-blacklisted.