There are something like 70,000 developers and 300,000 total employees, so it's hard to say anything other than "all of the above".
I mostly use Haskell and Perl. The rest of the department is mostly Perl. Sometimes I do C. Other groups are Python-heavy. There is a big Java and C# presence, and of course a lot of people that think C++ is the only real programming language.
There is some initiative to standardize on C++ and Python, but I doubt that is ever actually going to happen.
I recently went through financial difficulties that involved problems paying 5 different credit cards. Bank of America was by far the most helpful company, actually recommending that I enter into debt management to allow me to pay off my cards at a markedly lower APR without taking a huge hit to my credit.
Without getting into the evil/not evil argument: This is not quite correct. A bank can lend more money than they have/borrow. The bank must only maintain a specific ratio of equity and loans. For more details see Basel I, Basel II and the upcoming Basel III, which (should) regulate the loans of banks.
I mostly use Haskell and Perl. The rest of the department is mostly Perl. Sometimes I do C. Other groups are Python-heavy. There is a big Java and C# presence, and of course a lot of people that think C++ is the only real programming language.
There is some initiative to standardize on C++ and Python, but I doubt that is ever actually going to happen.