I'm sure you've had the comment, " Oooh , nice haircut" after a trim. The visit to the hairdressers has stopped people in their tracks, made them think about your hair as it was and compare it to how it is. This, in IT terms, is the "big bang" approach and is used to put out new pieces of functionality/design in one hit. It generally requires a lot of project management, change management and communications and is inherently risky - all or nothing. Of course sometimes the big bang approach can't be avoided: corporate re-brand, e.g. BNZ as of today introduction of new legislation, e.g. new NZ personal tax bands as of today introduction of brand new functionality, e.g. Google Moderator as of a few days ago ( learn more ) However, many (most?) pieces of software do not need a complete visit to the hairdressers with such a dramatic change. They are like the everyday combing, curling and general coiffuring that we all do to make it a bit better. And, like