Facebook is spreading read receipts a bit farther afield today: after launching the feature on Facebook Messenger in May, the company is now displaying the info on Group pages. This means that all posts on a Group page (on the web or mobile) now have a small "Seen by X" button that shows exact users when you hover over it. The feature certainly makes sense for Groups — the idea being that it's easy to confirm that everyone has seen a post without explicitly asking — but should Facebook ever decide to roll it out to the News Feed or Wall users may not be particularly accepting of the feature. For now, it looks like you've lost one more excuse for forgetting to bring desert to that once-monthly Parent Teacher Association meeting.