MNSSHP is actually at WDW. At California Adventure they have Mickey's Trick or Treat Party. Tickets are on sale now for AP holders and also if you have a Disney Visa.
Here is some more info:
The
Disneyland Resort's popular Halloween party is coming back for 2008 with a new name Mickey's Trick-or-Treat Party and Annual Passholders can take advantage of a special opportunity to purchase advance tickets. Plus, save with discounted prices on select dates!
This "spirited" event at Disney's California Adventure Park includes:
Amazing attractions to get you spinning, looping and free-falling.
Lively music to boogie your bones.
Trick-or-Treat for candy at treat stations.
Fun crafts and activities for some family fun.
A nightly Character cavalcade.
Enjoy an unforgettable evening of Disney Halloween fun for everyone!
Complimentary parking for one vehicle at the Mickey & Friends Parking Structure larger vehicles may require an additional fee.
Passholder Discount Available for Event Dates
October 3, 16, 22, 23, 28, 29
Passholder Discount Not Available for Event Dates
October 10, 17, 24, 30
Only Day of Event Tickets Available on Event Date
October 31
Event Times
Monday to Thursday 6:30 p.m. to 10:30 p.m.
Friday to Sunday 7:30 p.m. to 11:30 p.m.
Ticket Prices
Passholder Advance Ticket: $25 Only Available on Select Dates
General Advance Ticket: $29
Day Of Event Ticket: $37
Ages Two and Under: No Charge
Also both parks are totally decorated for the Halloween holiday and the decorations are amazing!!
The Haunted Mansion is also redone in a Nightmare Before Christmas theme.
It's a really fun time to be at the parks!!
(I probably have that name wrong). When do they become available? We're AP holders - does that make a difference? 
it's on the main page or you can click on special offers.
