The show is still on, but there are a few things to keep in mind.
1) I also haven't seen anywhere an official statement about how long it has been extended. My adivce here is to keep checking the boards here clost to your vacation and see if those who were at MK recently can confirm that it is still going. Additionally, just before you leave (a couple of days or so), try to call MK Guest Relations directly and ask them for the show times for the day you plan to be in MK. Tell them you are trying to put the final touches on your schedule for the day and need to find the best time to see the performance. If they give you show times, its still on (or hopefully anyway, provided the person working that day has accurate information - if they're smart, they'll look at the MK schedule to give you an answer).
2) The shows have been cut back somewhat from the summer schedule. Before we left, I checked the website (can't remember it now) where the person provides the show times at all the parks. I checked in on the day before we left (a Monday - the site owner says times are updated on Saturday nights, so the ones I saw were current), and he had a 6:15 (or close to that anyway) show listed. We went to MK on Wednesday (Sept. 6th) and discovered that the 5:15 and 6:15 shows no longer existed. The last one was at somewhere around 4pm. We, of course, went back on sunday to see the first one.
If they haven't changed since we were there last week, there should be four performances each day - two before noon and two in the afternoon.
BTW, the show IS fantastic - at least the person doing our performance. While not a dead ringer for Depp, the voice and mannerisms were near perfect - almost scary perfect.
Our six year old (picked as one of the "students" - AND, the one to challenge Jack rather than Mac!!!) truly thinks that he's met Jack Sparrow! He has watched "selected scenes" of the first Pirates movie - the creepy parts were cut out through my judicious use of the remote - and was absolutely convinced that the guy at MK was the same one in the movie.
Hope its still on for Nov. 
