It should be obvious that I'm not talking about work involving security clearances or explicit NDAs. I'm talking about the kind of work that most of us spend our time on -- data munging, HTML parsing, server monitoring, e-mail manipulation -- all that good stuff. Also, code samples are supposed to be short chunks of code that demonstrate your knowledge of programming concepts like encapsulation and good variable names. There's no need to bring in a complete program, or even complete file.

If someone walked into an interview with a bunch of code that handles money transfers for a major bank, I'd consider that pretty disturbing, but bringing in a snippet of code that calculates the right justification on a column in a PDF for some daily report is reasonable and does no real harm to anyone.

If it worries you, then don't do it, but you'd better find another way to create some code samples then. Hiring a programmer without a code sample is like hiring a writer without reading any of her work.