LostInTranslation from Brickset has found the two LEGO Halloween sets at LEGOLAND Billund, Denmark. There will be 2 mini promotional Halloween LEGO sets released for 2011 this year. One of them is LEGO 40020 (shown below) which comes with a ghost, bat and a pumpkin. The other one is LEGO 40021 which comes with 2 spiders. These 2011 Halloween promotional sets should be available at LEGO Brand Stores and Shop at Home very soon.
LEGO 40020 Halloween Set (71 pieces)