First off, Weather.com currently is predicting rain during the day of December 31st, so be prepared for really light crowds throughout the day, and possibly throughout the night should that happen! 
Daily Weather Forecast for Anaheim, CA - weather.com
Part 2:

Daily Weather Forecast for Anaheim, CA - weather.com
Part 2:
It looks like some events have been announced on the website, while others have not.
Disneyland, shockingly is only advertising two showings of Fantasmic! and not the third right after midnight, something that will change on the actual day when the crowds descend I bet.
Suburban Legends will be playing at the Terrace for the entire evening with the last show ending fifteen minutes prior to the 2AM park closing.
The Swing Party in Carnation Gardens will run up until 1AM this year.
Disneyland also hasn't even posted it's New Year Fireworks show on the site, though I'm quite sure it will be playing (cross your fingers there is no wind (08) and no fog (09).)
Oddly enough, Disney's California Adventure has some NYE stuff posted, but boy is it weird.
Something called DCA NYE 2009 Event Install has been listed in the new strange way Disney has found to list shows.
There is also DCA NYE 2009
Hopefully it will be better explained on the actual day! 
On top of it, Disney is not only planning just on a 8AM-2AM operating day, but will also be including Magic Morning. Making the day of operation go from 7AM-2AM. A whopping, 19 Hour Day!!
I'm very excited!
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Disneyland, shockingly is only advertising two showings of Fantasmic! and not the third right after midnight, something that will change on the actual day when the crowds descend I bet.
Suburban Legends will be playing at the Terrace for the entire evening with the last show ending fifteen minutes prior to the 2AM park closing.
The Swing Party in Carnation Gardens will run up until 1AM this year.
Disneyland also hasn't even posted it's New Year Fireworks show on the site, though I'm quite sure it will be playing (cross your fingers there is no wind (08) and no fog (09).)
Oddly enough, Disney's California Adventure has some NYE stuff posted, but boy is it weird.
Something called DCA NYE 2009 Event Install has been listed in the new strange way Disney has found to list shows.
2:00 p.m. to 10:30 p.m. 2:00 p.m. to 3:30 p.m. 6:00 p.m. to 8:00 p.m. 9:30 p.m.
7:00 p.m. to 1:00 a.m. 8:00 p.m. 9:30 p.m. to 1:00 a.m. 9:30 p.m. to 1:00 a.m. 11:45 p.m.

On top of it, Disney is not only planning just on a 8AM-2AM operating day, but will also be including Magic Morning. Making the day of operation go from 7AM-2AM. A whopping, 19 Hour Day!!
I'm very excited!

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