I catch one or more people cheating almost every semester. Most times, it's of the "cheat sheet on exams" variety. But sometimes, it involves plagiarism on a project.
I have less and less of a problem with it as time goes on, because I give very detailed guidelines as to what should go in each section of the project. So the likelihood that they'll be able to plagiarize something that matches up with the assignment's requirements is somewhere between slim and none. But still, it happens.
Here's a cautionary tale for those of you who have to do do group projects from Jacqueline Passey, who's now back to blogging (and with a new, improved title for her blog to boot). One of her group members plagiarized a good portion of her "contribution" to a group project in an accounting class. Luckily, Jacqueline caught it before handing it in and redid the work herself.
It's important to remember - if a member of your group plagiarizes on a joint project and the instructor catches it, you're equally screwed. So choose your group carefully, and check their work. If it has your name on it, you're responsible.
HT: Newmarks Door.
update 5/23: The link was to the wrong piece. It's been updated.