A.LeClair said:
All these Blade Runner fans and no one is willing to explain the tin foil animal ending to me!?
Okay - are you sitting comfortably? Okay, here goes...
...in the Director's Cut, Deckard (Harrison Ford) is shown sitting at his piano. He's been drinking and nods off into a dream about a Unicorn...
...at the end of the film Gaff (the character with the hat and the stick) leaves a tinfoil unicorn for Deckard to find.
This shows that Gaff knew what Deckard had been dreaming about and therefore implies that Deckard is also a Replicant - in the movie, the latest Replicants have implanted memories to enable them to handle emotions...
BUT, there has always been a MASSIVE debate between fans about whether Deckard is human or not. Ridley Scott (the Director) has gone on record as saying that he wanted Deckard to be a Replicant and that is why he inserted the unicorn scene.
Harrison Ford disagreed with Ridley and always thought Deckard should be human.
Philip K Dick, always said that Deckard was human in the original book "Do Androids Dream of Electric Sheep"...
...luckily the film is ambiguous enough to allow both possibilities.
Personally, I think the revelation that the main hero is non-human is the ultimate twist. After all, the whole movie is asking "what makes us human" and the very fact that you assume that Deckard is human right until the end, really pushes the point.