Is unit testing used and how often?

oriol writes: "It seems that a lot of people really think that writing unit tests is the best way to help and keep code working correctly on the long run. In my experience (of programming in a research environment), it is not that likely that software projects are equipped with unit tests. As I am quite interested by the subject I am conducting a small survey (5-10 mn to answer) on this topic to see if the situation is the same for everybody. What do you think fellow slashdotters?"