Portfolio theft? I'd say it's one of the highest crimes one programmer, designer (software, graphic, or any other kind), musician, artist, or engineer can commit against another in the context of work.

I know when I found a guy claiming pieces from the portfolio of mine and my former coworker on some freelancing site, I was entirely appalled. I expected them to kick him off the site, but all they did was make him remove the specific work I could prove wasn't his. Who knows how much of his supposed work is just ripped off from someone else? What I really wanted to do was pretend to pretend to want his services so I could negotiate a meeting and beat the living hell out of him. Thankfully, my cooler side prevailed. I'd probably have served the jail time he has, IMHO, earned.

Open source is great, and I have no problems with contributing to publicly available projects. Don't ever tell someone you did work that I did, though. That's fraud for one thing, and it's likely to harm my livelihood for another.

That includes listing programs you didn't program in your portfolio, taking other people's copyrights out of credits, inserting your name into credits for parts of a work you didn't do, and just generally claiming any work that isn't yours. Anyone who does such things should be banned from the industry.