Thanks for responding! We are hoping there is not one, as we would want to avoid the crowds it would bring. Currently we made non-Disney plans for that day but will definitely add a day on to our ticket if there is no 24 hour event. I'm getting anxious to finalize our plans so I hope they release this info soon!
Last year, they announced the 24-hour day in mid-March. So far there hasn't been any announcement, but there are rumors pointing both ways, so it's anyone's guess at this point. My inclination is to say either they will announce there will be a 24-hour day or there won't be any announcements at all (i.e., there won't be an announcement saying there is no 24-hours day).
Disneyland Today has been tweeting either that there are "no plans" or "no announcement at this time, but stayed tuned to the Parks Blog for the latest information" depending on the CM manning the Disneyland Today Twitter feed.