Working in the Java world has made a lot of developers aware of the importance of tests. A good series of tests can catch regressions early and allows us to be more confident when we ship our product.
A lot of people are now familiar with the notion of continuous integration (http://www.thoughtworks.com/continuous-integration). This is a practice where a server is in charge of building the application every time a change is made on the source control system.
The build should be as fast as possible and capable of self testing. The main idea of this practice is to get a fast feedback loop; you should get details about what went wrong as soon as something in the system breaks.
Why should you care? After all, testing your application is an additional cost; the time spent designing and maintaining tests will necessarily eat into some development time.
Actually, the later a bug is found, the costlier it gets. If you think about it, even a bug found by your QA team begins...