This has a pretty good layman's explanation as well as how banks are being affected by the current economic turmoil.

http://www.thislife.org/Radio_Episode.aspx?episode=375

In my case, I am actually much more interested in econ. and business. CS is just something I do as well, thus my interest in banking regulation, accounting, and valuations techniques (though I am, by no means, an expert on any of those subjects...).

As it so happens, CS people are much better at computers than economists etc... though there are some excellent econ. blogs on the internet which I enjoy reading.

Its a matter of specialization. I just happen to have banks as on of the things I try to specialize in.