It's an art you should try to improve. It's called the elevator pitch, how to tell a stranger in 30 seconds what do you do in words she can understand, whatever her background.
I've found that talking about what do your programs mostly do (the what) is more helpful than what do you actually do (the how). This is a bit counterintuitive, because for us the how is the most interesting part (holy wars, learning new technologies, etc.)
For instance, instead of "I use .NET Remoting to call Web Services that deliver the stock quotes via a Java Application Platform that is down a lot of the time" go "I design systems to help my company get stock quotes"