Why So Socialist?

Apparently these posters are popping up in Los Angeles. Hopefully it will spread like wildfire throughout the country. So what can one make out of the poster? Is it implying the Joker was a socialist? Or was Heath Ledger a socialist?

Possible interpretations:
Obama = Joke
The Joker = Sociopath
The Joker aims to bring about the collapse of society and anarchy. Obama seems to have a similar intent and bring about socialist utopia.

Now the question is, who will be The Batman? Ron Paul? Paul Ryan?