Is it possible for web developer to work in a bank?
All the IT roles that Banks need requires knowledge of C++,C# or Java. I don't really see any opening for web developers at all.
Bank Simple (http://banksimple.com), they're currently looking for front-end dev's. It's possible but most large banks don't care about their web presence and most wouldn't be looking for PHP developers.
The web is a platform - it shouldn't matter what the language is.
Why would banks hire someone without the proper skillset?