As my Facebook profile has come to prove, it's too easy for me to pass up! And I feel like a pretty lucky person, so maybe it's working ;)
The exact origin of the superstition is unknown, though it has appeared in print at least as early as 1922:
'Why,' the man in the brown hat laughed at him, 'I thought everybody knew 'Rabbit, rabbit, rabbit.' If you say 'Rabbit, rabbit, rabbit'--three times, just like that--first thing in the morning on the first of the month, even before you say your prayers, you'll get a present before the end of the month.'
However, some reports place its origins even earlier, into the 1800s. Today it has spread to most of the English-speaking countries of the world, although like all folklore, determining its exact area of distribution is difficult. This superstition is related to the broader belief in the rabbit or hare being a "lucky" animal, as exhibited in the practice of carrying a rabbit's foot for luck. Some have also believed it is representing a jumping into the future and moving ahead with life and happiness.
No matter how you look at it, I'm celebrating the first of November with this Rabbit, rabbit post, and a picture of a bunny with a pancake on his head. Enjoy :)