Who are TeaMp0isoN and what is Operation Robin Hood?

TeaMp0isoN, a black-hat hacking collective, has announced that it is to collaborate with Anonymous on Operation Robin Hood which swears to take money from the banks (in the form of stolen credit card data) and redistribute the wealth from the 1% to the 99% in support of the Occupy Movement. But just who exactly are TeaMp0isoN and what impact is Operation Robin Hood likely to have?