Why has Live Preview been disabled?

Live Preview is great technology. Kind of mandatory. You get links compiled to see if they are working correctly before you post. After maintenance last night it did not work, and does not work this morning.

There is a (related?) bug, as I’m not able to post a new comment into the “Do dogs have a subconscious mind?” question. I hit [Answer] and nothing happens. I refresh, etc., nothing happens. FYI (latest Firefox, latest XP-SP3)